• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    A broadband self-powered UV photodetector of a β-Ga2O3/γ-CuI p-n junction

    2022-02-24 09:39:46WeiMingSun孫偉銘BingYangSun孫兵陽ShanLi李山GuoLiangMa麻國梁AngGao高昂WeiYuJiang江為宇MaoLinZhang張茂林PeiGangLi李培剛ZengLiu劉增andWeiHuaTang唐為華
    Chinese Physics B 2022年2期
    關(guān)鍵詞:李山高昂茂林

    Wei-Ming Sun(孫偉銘), Bing-Yang Sun(孫兵陽), Shan Li(李山), Guo-Liang Ma(麻國梁),Ang Gao(高昂), Wei-Yu Jiang(江為宇), Mao-Lin Zhang(張茂林),Pei-Gang Li(李培剛), Zeng Liu(劉增),?, and Wei-Hua Tang(唐為華),,?

    1Laboratory of Information Functional Materials and Devices,School of Science,Beijing University of Posts and Telecommunications,Beijing 100876,China

    2College of Integrated Circuit Science and Engineering,Nanjing University of Posts and Telecommunications,Nanjing 210023,China

    3National and Local Joint Engineering Laboratory for RF Integration and Micro-Packing Technologies,Nanjing University of Posts and Telecommunications,Nanjing 210023,China

    The symmetric Ti/Au bi-layer point electrodes have been successfully patterned on the β-Ga2O3 films which are prepared by metal–organic chemical vapor deposition(MOCVD)and the γ-CuI films which are prepared by spin-coating.The fabricated heterojunction has a large open circuit voltage(Voc)of 0.69 V,desired for achieving self-powered operation of a photodetector.Irradiated by 254-nm ultraviolet (UV) light, when the bias voltage is ?5 V, the dark current (Idark)of the device is 0.47 pA,the photocurrent(Iphoto)is ?50.93 nA,and the photo-to-dark current ratio(Iphoto/Idark)reaches about 1.08×105.The device has a stable and fast response speed in different wavelengths, the rise time (τr) and decay time(τd)are 0.762 s and 1.741 s under 254-nm UV light illumination,respectively.While the τr and τd are 10.709 s and 7.241 s under 365-nm UV light illumination,respectively.The time-dependent(I–t)response(photocurrent in the order of 10?10 A)can be clearly distinguished at a small light intensity of 1μW·cm?2.The internal physical mechanism affecting the device performances is discussed by the band diagram and charge carrier transfer theory.

    Keywords: β-Ga2O3,γ-CuI,heterojunction,broadband photodetector,self-power

    1.Introduction

    UV light can be divided into four regions according to different wavelengths, short-wave UV light referred to as UVC,wavelength of 200 nm–280 nm,medium-wave ultraviolet light referred to as UVB,wavelength of 280 nm–320 nm,long-wave ultraviolet light referred to as UVA, wavelength of 320 nm–400 nm, UVD wavelength of 100 nm–200 nm, also known as vacuum UV light.UV light was first discovered in 1801,and its applications have come a long way since then.UVA light can be completely cut off through the visible light of the special-colored glass lamp tube,only emit 365 nm as the center of the near UV light, can be used for ore identification,banknote inspection and other purposes; UVB can be used to make UV health lamp, plant growth lamp; UVC is widely used in UV sterilization industry; in addition, UV light has been applied and received widespread attention in space optical communication,deep UV imaging,environmental monitoring,missile guidance,flame detection,and other fields.[1–3]

    In these studies,the accurate detection of UV wavelength is an important research direction.[4–8]In the past few decades,a series of wideband gap semiconductors for UV light detection have been studied, such as GaN[9]for UVA, ZnMgO[10]for UVB, Ga2O3[11,12]for UVC, and AlN[13]for UVD.Different semiconductor materials have different bandgap widths,which determine their responsiveness at specific UV wavelengths.Therefore, the effect of bandgap width on the performance of photodetector is very important.The semiconductor combination with different bandgaps can extend the response spectrum to a wider wavelength and realize the broadband UV detection.Therefore, it is an important strategy to improve the performance of photodetectors to select appropriate bandgap semiconductors to separate the photoelectron–hole pair and adjust the absorption edge of the heterogeneous structures.In recent years, GaN, SiC, Ga2O3, and other third-generation semiconductor materials with a bandgap of more than 3 eV have been widely studied.[14–19]These materials have the advantages of wide bandgap, high electric field breakdown strength, high saturated electron drift speed, and good chemical and thermal stabilities,etc., which are very suitable for the study of high-performance semiconductor devices.The bandgap of β-Ga2O3ranges from 4.2 eV to 4.9 eV,covering the main UVC region, making it an ideal material for preparing solar-blind UV photodetectors, and the heterojunction structure based on β-Ga2O3is an effective attempt to broaden the detection region.A solar-blind photodetector based on a β-Ga2O3/4H–SiC p–n heterojunction showing ultrahighIphoto/Idarkof more than 103responding to light irradiation with intensity of 91 μW/cm2has been reported.[20]In addition, the heterojunction UV photodetector based on that of the Cs3Cu2I5/β-Ga2O3with highIphoto/Idarkof ~5.1×104at zero bias,[21]β-Ga2O3/MgO with ultrahigh responsivity of 2.4×107A/W and detectivity of 1.7×1015Jones(1 Jones=1 cm·Hz1/2·W?1),[22]and the MXenes/β-Ga2O3high-performance solar-blind photodetectors with responsivity of 12.2 mA·W?1and detectivity of 6.1×1012Jones at zero bias[23]were achieved.

    For β-Ga2O3-based heterojunction, the key problem in achieving true full UV detection is that the spectral response will decrease rapidly at a longer wavelength determined by a smaller bandgap.[24]Therefore,to achieve a spectral response cutoff of 400 nm,a band gap of a constituent material should be around 3.1 eV.Among typical inorganic materials,CuI is a good candidate with a bandgap of 3.1 eV.[25–27]β-Ga2O3/γ-CuI combination can form the classical type-II p–n heterojunction, and its internal photoelectric effect lays the foundation for the self-power supply of photodetectors.

    In this work,a kind of broadband ultraviolet self-powered photodetector is constructed by a lateral β-Ga2O3/γ-CuI heterogeneous structure.The performance of the device under different biasing voltages and light intensities is systematically studied, and the internal physical mechanism of the device is discussed by energy band structure and carrier transport theory.The designed photodetector has decent self-powered performances in the full UV spectrum, and has a broad application prospect in the multi-spectral energy-saving photo detection.

    2.Experimental details

    Undoped β-Ga2O3thin films were prepared on the wafer size (2-inch, 1 inch=2.54 cm) Al2O3substrate by MOCVD method.Oxygen was used as the oxygen source,Triethylgallium(TEGa)was chosen to be used as the gallium source,and the carrier gas was argon(Ar).At the temperature of 500°C and pressure of 25 Torr(1 Torr=1.33322×102Pa),the growth rate of about 1μm·h?1can be achieved.

    CuI thin films were prepared by spin coating method.First,2-mL 20-mg/mL CuI solution was prepared.0.04-g CuI powder was weighed by electronic balance.The solvent was chlorobenzene:dipropyl sulfide with a volume ratio of 19:1.In the following,1.9-mL chlorobenzene and 0.1-mL dipropyl sulfide with an eyedropper were put into a small brown bottle that has been cleaned,then we put a stirring magneton into it, seal it and stir it in an electromagnetic mixer for 3 h.In the case of the heterojunction construction, the wafer size β-Ga2O3film was cut into small pieces(10 mm×10 mm),then cover part of the film with tape, place the sample on the center platform of the spinner,40-μL solution was dispensed onto the center of the sample(β-Ga2O3film),after that it was spin coated for 30 s at a rotate speed of 4000 rpm.After baking at 120°C for 15 min,the tape on the β-Ga2O3film was released.Then, the electrode mask was covered on the thin films, and 30-nm Ti and 70-nm Au were deposited as contacted electrodes by direct-current magnetron sputtering technique.Ultimately,the corresponding device was finished in fabricating as displayed in Fig.1(a).

    3.Results and discussion

    As shown in Fig.1(b),the x-ray diffraction(XRD)pattern of the MOCVD-grown β-Ga2O3film is displayed,indicating a high quality monocrystal along, andorientations.The XRD pattern of the CuI thin film is demonstrated in Fig.1(c),from which a strong peak of(111)located at 25.47°and a weak peak of (222) located at 52.55°are observed, indicating a cubic structure of CuI.As presented in Fig.1(a), a three-dimensional schematic diagram of the device is shown.One end of the electrode is on the surface of β-Ga2O3and the other end is on the surface of γ-CuI to ensure that the current passes through the contact surface.Figure 1(d)shows the scanning electron microscope (SEM) image of the crossing section of the film-based heterojunction, indicating that the thicknesses of the Ga2O3and CuI films are 500 nm and 30 nm,respectively.

    Fig.1.Device morphology characterization (a) The three-dimensional schematic diagram of device structure, (b) the XRD pattern of β-Ga2O3,(c)the XRD pattern of γ-CuI,and(d)the cross-sectional SEM image of the heterojunction structure device.

    To investigate the optoelectrical characteristics of the device, 4200 digital sourcemeter instrument was employed.In order to verify the effect of junction effect on device performances, two single-layer thin film metal–semiconductor–metal (MSM) devices were fabricated and their performance were tested.The current–voltage (I–V) characteristics of β-Ga2O3and γ-CuI MSM devices are shown in Figs.2(a) and 2(b), respectively.TheI–Vcurves of the two MSM devices in the dark and under UV light illuminations are almost linear,suggesting both decent Ohmic contacts.γ-CuI MSM device has a large dark current(up to 4.0μA at 5 V),and the current becomes larger(up to 25.0μA at 5 V)when 254-nm UV light is turned on.While,in comparison,the β-Ga2O3MSM device has a small dark current (only 0.27 pA at 5 V), and the current becomes larger(86.3 nA at 5 V)under 254-nm UV light illumination.According to the electrical results by measurements in Figs.2(a)and 2(b),we could obtain the conductivities of 0.173 μS·cm?1(254-nm UV light), 1.24×10?7μS·cm?1(dark) for Ga2O3, and 51.3 μS·cm?1(254-nm UV light),8.7μS·cm?1(dark)for CuI,respectively.Therefore,the conductivity of CuI thin film is higher than Ga2O3, apparently.Ga2O3is a typical n-type transparent semiconducting oxide,and its conductivity is relatively low in the dark.However,due to the high absorption of light at 254-nm wavelength, photogenerated carriers are generated,and the conductivity is significantly improved after illumination.For the CuI film, a good Ohmic contact is achieved and it also has absorbance at 254-nm wavelength light (far weaker than Ga2O3), so it has high conductivity under light/dark conditions.

    Figure 2(c) shows theI–Vcharacteristic curve of γ-CuI/β-Ga2O3heterojunction device.The dark current of the device fluctuates in a low range(0.1 pA–2.0 pA),and the device exhibits obvious rectification effect and photovoltaic effects under the irradiation of UV light with the illumination intensity of 500μW·cm?2.When the biasing voltage is ?5 V,the dark current of the device is as low as 0.47 pA, the photocurrent is ?50.93 nA, and the PDCR reaches as high as 1.08×105.The asymmetrical photo responses at either positive or negative biases voltage show that the heterojunction structure has rectification effect.It can be seen from theI–Vcurve that the open circuit voltage (VOC) of the device is about 0.69 V, and it still responds to the UV light irradiation of 254 nm at zero bias(the photocurrent of ?2.69 nA),owing to the achievement of photovoltaic effect in the Ga2O3/CuI heterojunction.

    When the p–n junction is illuminated, the absorption of photons by the device will generate photo-generated carriers,and the intrinsic carriers will diffuse to the vicinity of the junction, drift under the action of the internal electric field, and complete the electron–hole pair separation,thus form a potential difference near the p–n junction boundary and generating photocurrent.In addition,the photo-generated carriers obtain greater energy under the acceleration of the electric field in the junction region and further collide to produce more carriers,thus generating the gain of the photocurrent.Therefore,the device has the potential to be a self-powered photodetector.

    Fig.2.The I–V characteristics of (a) Au/Ti/γ-CuI/Ti/Au MSM device, (b) Au/Ti/β-Ga2O3/Ti/Au heterojunction device, and (c) Au/Ti/β-Ga2O3/γ-CuI/Ti/Au heterojunction device in the dark and under light illumination with an intensity of 500 μW·cm?2. The insets in panels (a) and (b) show the corresponding structure diagrams of each MSM device. The inset in panel(c)shows the dark current of less than 1 pA.

    Fig.3.(a)The I–V response curves of γ-CuI/β-Ga2O3 heterojunction devices under different illumination intensities. Panels(b)and(c)are the curves of the responsiveness and specific detection rate of the device with different illumination power densities under the biasing voltages of 0 V and 5 V,respectively.

    TheI–Vcharacteristics of γ-CuI/β-Ga2O3heterojunction device was further explored,and theI–Vresponses of the device under different illumination intensities were measured,as shown in Fig.3(a).Figures 3(b) and 3(c) show the changes of responsivity and specific detection rate of the device with different illumination power densities.It can be seen from the image that the photo response of the device changes regularly with the change of illumination power density.These curves show that the device can operate stably under different light intensities,and the photo response of different light intensities has a certain degree of differentiation.

    TheI–tresponse of the device under different conditions is investigated.Figures 4(a) and 4(b) show theI–tresponse curves of 254 nm, under 500-μW·cm?2light, different bias voltages and 254 nm, 0-V bias voltage, different light intensities, respectively.As can be seen from Fig.4(a), under a certain illumination power density,the photocurrent increases regularly with the increase of bias voltage.In this figure, under 500-μW·cm?2illumination, in the range of 0 V–5 V, the photocurrent increases by about 10 nA for every 1-V increase of voltage.In addition,the device also shows a fast and stable response speed.This kind of good photoelectric characteristic is beneficial to improve the performance of photoelectric detector.Figure 4(b) shows a test of the device’s self-supply performance.In the absence of applied bias voltage, the device still exhibits a good optical response to 254-nm light,and the nanoscale photocurrent is competent to realize the function of photodetector in the case of self-powered.

    Fig.4.The I–t response curves of (a) to the 254-nm UV light with an intensity of 500μW·cm?2 under different bias voltages and(b)to the 254-nm UV light with different intensities under a bias voltage of 0 V.The inset of (b) shows the I–t response curve of a heterojunction device with a light intensity of 1μW·cm?2 at a 5-V biasing voltage.

    TheI–tresponse of the device under small light intensity is also studied.Figure 4(b)shows theI–tresponse of the device at a light power density of 1 μW·cm?2.It can be seen from this figure that the device still generates a clear and observableI–tresponse to 254-nm light (the photocurrent is in the order of 0.1 nA) even under the low light intensity, indicating that the device has the potential to realize UV detection under the low light intensity.

    Fig.5.Panels (a) and (b) respectively show the transient response and fitting results of the heterojunction device under the bias voltage of 3 V and the light power density of 500μW·cm?2 at 254-nm and 365-nm ultraviolet light.The data points are the transient response of the heterojunction device,and the lines are the fitting results.

    The transient response of γ-CuI/β-Ga2O3heterojunction devices was investigated.Figures 5(a)and 5(b)shows the transient response and fitting results of the device under UV light at 254 nm and 365 nm respectively.The process of current rise and decay of the device is fitted, and the second-order exponential equation used to fit theI–tcurve:

    whereI0is the steady-state photocurrent,AandBare constants,Tis time, and τ is the relaxation time constant.The rise time(τr)and decay time(τd)of the ultraviolet response of different bands are fitted under the same bias voltage of 3 V.At 254-nm light,the rise time(τr)and decay time(τd)are 0.762 s and 1.741 s, respectively.At 365 nm, the rise time (τr) and decay time(τd)are 10.709 s and 7.241 s,respectively.This indicates that the device has a faster response at 254 nm than at 365 nm.By the irradiation of 254-nm light, photo-generated carriers mainly come from valence–conduction band transition.However, by the irradiation of 365-nm light, the generation of photo-excited carriers are only from the defect–conduction band transition.During the photo-excited process,valence–conduction band transition is the main way.So, theIphotounder 254-nm light illuminations is much larger than that of 365-nm UV light.Meanwhile, some of the photo-excited carriers may well be captured by the trapping states in film.For the decaying process, the recombination of the carriers determines the decay time, and the fast decay speed is fact owing to the less trapping and the trapping states would be released and recombined.[28,29]What is worthy to be noted is that the irradiated source is a monochromatic lamp which could emit 254-nm UV light.When performing theI–tmeasurements, the UV lamp may illuminate the whole surface of the heterojunction photodetector.The light intensity could be changed by tunning the distance between the device and the lamp, where the intensity can be read through a display instrument.The optical switching behavior is owing to the reaction between the 254-nm and 365-nm UV light and the semiconductors in this heterojunction,[30]the incident photons excite the photo-generated electron–hole pairs for achieving the time-dependent optical switching phenomenon,as the UV lamp was turned on and turned off.

    The spectral response range of γ-CuI/β-Ga2O3heterojunction device was measured, as shown in Figs.7(a) and 7(b).The spectral responsiveness with the cutoff wavelength of 410 nm proves that it has a certain broadband UV sensing capability.The UVC/UVA inhibition ratio(R225/R400)of the device is 5.58×102, which shows a certain spectral selectivity.In the spectrum,RandDhave obvious attenuation at 255-nm and 410-nm light,which is consistent with the absorption cutoff wavelengths of Ga2O3and CuI.Ga2O3response positively to UVC light, but less response to UVA light; while CuI showed stronger carrier productivity under UVC light.Therefore, β-Ga2O3/CuI heterojunction has a high photo response in the UVC region and a low photo response in the UVA region[24]at 0 V and 5 V,as displayed in Fig.6.

    In order to confirm the role played by γ-CuI/β-Ga2O3heterojunction structure, the intrinsic physical mechanism of device operation was explained by the diagram of carrier transport mechanism and heterojunction band, as shown in Fig.7.It can be seen from the band diagram that there is a certain difference betweenEF(N)andEF(P)when n-type and p-type semiconductors exist alone.When n-type and p-type semiconductors are in close contact,electrons will flow from the high Fermi level to the low Fermi level, and the holes will flow in the opposite direction.At the same time, an internal electric field is generated.The direction of the internal electric field is from n region to p-region.Under the action of the internal electric field,EF(N)will move down together with the whole band in the n-region,andEF(P)will move up together with the whole band in the p-region,until the Fermi levelEFis leveled toEF(N)=EF(P),and the flow of charge carriers stops.At this time, the conduction band and valence band of the junction region bend accordingly,forming a potential barrier.

    Fig.6.Spectral response curves of heterojunction devices at 5-V bias voltage(blue dot line)and 0-V bias voltage(red dot line).

    Fig.7.The band diagrams of γ-CuI/β-Ga2O3 heterojunction under 254-nm ultraviolet light(a)and(b).

    It is reported that when the band gap of Ga2O3is 4.86 eV,the valence band (VB) value is 7.95 eV and the conduction band(CB)value is 3.09 eV.When the band gap value of CuI is 2.98 eV,the valence band(VB)value is 2.22 eV and the conduction band(CB)value is 5.20 eV.The band structure of the heterojunction can form a typical type-II heterojunction.The diffusion and movement of the intrinsic charges cause band bending, creating a depletion layer at the interface.Since the photon energy is larger than the band gap value(hc/λ >Eg),when the heterojunction is irradiated by ultraviolet light of λ < 255 nm, the ground state electrons in VB in CuI and Ga2O3can be excited by absorbed photons and further transition into CB.Meanwhile, the photogenerated electron–hole pair in the depletion layer is separated by the built-in electric field near the heterojunction interface.The electrons are transferred from CB of CuI to CB of Ga2O3,and the holes are transferred from VB of Ga2O3to VB of CuI.

    However, it should be pointed out that the optical response performance of the device is different in the UVA region and the UVC region.The device has a high responsivity in the UVC region (λ <255 nm), but the responsivity is slightly reduced at 255 nm< λ < 10 nm.This is because the energy ofhc/λ is low, the VB ground state electrons of Ga2O3cannot be excited,and the concentration of photogenerated carrier is less than that in the UVA region,as a result of the slightly worse performance.

    4.Conclusions

    In summary, we successfully prepared β-Ga2O3thin films on Al2O3substrate by MOCVD method, and then prepared γ-CuI/β-Ga2O3heterojunction by spin coating CuI thin films on Al2O3substrate.When the bias voltage is ?5 V,the dark current and photocurrent of the detector are 0.47 pA and ?50.93 nA,and the ratio of light-to-dark current reaches 1.08×105.At 254 nm, the rise time (τr) and decay time (τd)are 0.762 s and 1.741 s,respectively,indicating a fast response speed.TheI–ttest shows that the device has good stability and response speed under different illumination power densities and bias voltages.In addition, thanks to the heterojunction structure and internal photoelectric effect,the device can work under unbiased voltage,and has the potential to become a self-powered photodetector.In conclusion,this β-Ga2O3/γ-CuI heterojunction wide ultraviolet photoelectric detector has a broad application prospect in the field of multispectral applications and self-powered energy-saving devices due to its excellent performance.

    Acknowledgement

    Project supported by the National Natural Science Foundation of China(Grunt No.61774019).

    猜你喜歡
    李山高昂茂林
    Origin of the low formation energy of oxygen vacancies in CeO2
    高昂書法作品欣賞
    驢殤
    驢殤
    短篇小說(2021年2期)2021-04-29 11:22:36
    《厲害了,我的國》觀后感
    我的太行
    黃河之聲(2018年21期)2018-10-21 17:40:24
    我不是乞丐
    李茂林藏石欣賞
    寶藏(2017年11期)2018-01-03 06:45:55
    Material microstructures analyzed by using gray level Co-occurrence matrices?
    李茂林 藏石欣賞
    寶藏(2017年7期)2017-08-09 08:15:18
    国产伦人伦偷精品视频| 国产精品亚洲av一区麻豆| 久久综合国产亚洲精品| 狂野欧美激情性bbbbbb| 国产在线观看jvid| 天堂中文最新版在线下载| 欧美日韩福利视频一区二区| 国产免费视频播放在线视频| 国产精品国产三级国产专区5o| 国产精品麻豆人妻色哟哟久久| 90打野战视频偷拍视频| 别揉我奶头~嗯~啊~动态视频 | 一二三四社区在线视频社区8| 中国美女看黄片| 日本猛色少妇xxxxx猛交久久| 夜夜骑夜夜射夜夜干| 欧美+亚洲+日韩+国产| 国产91精品成人一区二区三区 | 日本猛色少妇xxxxx猛交久久| av不卡在线播放| 女人高潮潮喷娇喘18禁视频| 亚洲九九香蕉| 精品一区二区三区四区五区乱码| 王馨瑶露胸无遮挡在线观看| 国产亚洲av片在线观看秒播厂| 人人妻人人澡人人爽人人夜夜| 美女主播在线视频| 真人做人爱边吃奶动态| 日本五十路高清| 亚洲中文av在线| 欧美日韩成人在线一区二区| 一级毛片电影观看| 狂野欧美激情性bbbbbb| 亚洲av美国av| 日韩有码中文字幕| 精品卡一卡二卡四卡免费| 纯流量卡能插随身wifi吗| 亚洲男人天堂网一区| 18在线观看网站| 国产男女内射视频| 侵犯人妻中文字幕一二三四区| 成年动漫av网址| 高清黄色对白视频在线免费看| 国产精品亚洲av一区麻豆| av电影中文网址| 十八禁高潮呻吟视频| 国产男女超爽视频在线观看| 99久久国产精品久久久| 女人爽到高潮嗷嗷叫在线视频| www.自偷自拍.com| 精品国产乱码久久久久久男人| av片东京热男人的天堂| 不卡av一区二区三区| 新久久久久国产一级毛片| 国产高清国产精品国产三级| 亚洲精品第二区| 少妇被粗大的猛进出69影院| 香蕉国产在线看| 久久综合国产亚洲精品| www.自偷自拍.com| 51午夜福利影视在线观看| 久久久久视频综合| 久久国产精品影院| 男女床上黄色一级片免费看| 如日韩欧美国产精品一区二区三区| 久久影院123| 日韩中文字幕欧美一区二区| 精品人妻熟女毛片av久久网站| 亚洲色图 男人天堂 中文字幕| 两个人看的免费小视频| 动漫黄色视频在线观看| 女人久久www免费人成看片| 美女主播在线视频| 夜夜骑夜夜射夜夜干| 欧美av亚洲av综合av国产av| 最近最新免费中文字幕在线| 黄色怎么调成土黄色| 999久久久精品免费观看国产| 免费在线观看完整版高清| 一区二区三区精品91| 久久人人爽av亚洲精品天堂| 婷婷色av中文字幕| 亚洲av电影在线进入| 菩萨蛮人人尽说江南好唐韦庄| 国产成人a∨麻豆精品| 99国产极品粉嫩在线观看| 国产一区二区三区在线臀色熟女 | 十八禁高潮呻吟视频| 黄色视频,在线免费观看| 视频区图区小说| 99久久综合免费| 成人国产一区最新在线观看| 亚洲国产精品一区二区三区在线| 亚洲欧洲精品一区二区精品久久久| 九色亚洲精品在线播放| 99国产精品免费福利视频| 制服诱惑二区| 天天躁日日躁夜夜躁夜夜| av在线app专区| 亚洲九九香蕉| 亚洲欧洲精品一区二区精品久久久| 久久久精品区二区三区| 欧美日韩中文字幕国产精品一区二区三区 | 少妇精品久久久久久久| 久久精品成人免费网站| av国产精品久久久久影院| 成年av动漫网址| 老司机影院毛片| 欧美黄色淫秽网站| 午夜两性在线视频| 国产成人精品在线电影| 午夜成年电影在线免费观看| 飞空精品影院首页| videosex国产| 大片电影免费在线观看免费| 啦啦啦啦在线视频资源| 肉色欧美久久久久久久蜜桃| 中国国产av一级| 午夜视频精品福利| 亚洲九九香蕉| 丰满迷人的少妇在线观看| 婷婷成人精品国产| 中文字幕另类日韩欧美亚洲嫩草| 中文字幕最新亚洲高清| 12—13女人毛片做爰片一| av有码第一页| 夫妻午夜视频| 亚洲av成人不卡在线观看播放网 | 韩国高清视频一区二区三区| 国产精品av久久久久免费| 自拍欧美九色日韩亚洲蝌蚪91| 97人妻天天添夜夜摸| 欧美黄色片欧美黄色片| 两人在一起打扑克的视频| 岛国在线观看网站| 国产一区二区三区综合在线观看| 一进一出抽搐动态| 国产精品1区2区在线观看. | 国产深夜福利视频在线观看| 母亲3免费完整高清在线观看| 中国国产av一级| 18禁观看日本| av网站免费在线观看视频| av天堂久久9| 亚洲精品国产av蜜桃| 欧美激情高清一区二区三区| 中国国产av一级| 999久久久国产精品视频| 日韩欧美免费精品| 国产精品一区二区免费欧美 | 国产成人啪精品午夜网站| 啦啦啦啦在线视频资源| 国产免费福利视频在线观看| 精品少妇久久久久久888优播| 亚洲av成人不卡在线观看播放网 | 亚洲精品国产区一区二| 日韩欧美免费精品| 中文字幕最新亚洲高清| 午夜精品国产一区二区电影| 午夜福利在线观看吧| 午夜精品国产一区二区电影| av在线播放精品| 成人国产一区最新在线观看| 1024视频免费在线观看| 99九九在线精品视频| 日韩欧美一区视频在线观看| tocl精华| 午夜福利影视在线免费观看| 中文字幕人妻丝袜一区二区| 色婷婷av一区二区三区视频| 激情视频va一区二区三区| 女性生殖器流出的白浆| 伦理电影免费视频| 国产精品麻豆人妻色哟哟久久| 亚洲激情五月婷婷啪啪| 欧美乱码精品一区二区三区| 亚洲av美国av| 亚洲avbb在线观看| 成人国产一区最新在线观看| 嫁个100分男人电影在线观看| 在线观看免费高清a一片| 国产在线观看jvid| 一进一出抽搐动态| 国产精品一二三区在线看| 午夜福利在线免费观看网站| 亚洲avbb在线观看| 亚洲全国av大片| 一级黄色大片毛片| 搡老乐熟女国产| 欧美日韩亚洲高清精品| 亚洲一码二码三码区别大吗| 男男h啪啪无遮挡| 国产淫语在线视频| 69精品国产乱码久久久| a 毛片基地| 日韩三级视频一区二区三区| 高清在线国产一区| 国产日韩欧美在线精品| 18禁黄网站禁片午夜丰满| 下体分泌物呈黄色| www.av在线官网国产| 精品久久蜜臀av无| 欧美 日韩 精品 国产| 黄频高清免费视频| 91大片在线观看| 精品人妻1区二区| 18在线观看网站| 亚洲欧美一区二区三区久久| 亚洲精品美女久久av网站| 色综合欧美亚洲国产小说| 欧美日韩黄片免| 中文字幕另类日韩欧美亚洲嫩草| 天堂8中文在线网| 在线观看一区二区三区激情| 一区二区av电影网| 999精品在线视频| 日本a在线网址| 淫妇啪啪啪对白视频 | 国产成人精品久久二区二区91| 国产精品一区二区免费欧美 | 丰满迷人的少妇在线观看| 国产在线一区二区三区精| 色精品久久人妻99蜜桃| 欧美性长视频在线观看| 视频区欧美日本亚洲| www.精华液| 欧美亚洲日本最大视频资源| 日本a在线网址| 亚洲 欧美一区二区三区| 久久国产精品男人的天堂亚洲| 两性夫妻黄色片| 老司机亚洲免费影院| 亚洲国产日韩一区二区| 91大片在线观看| 亚洲国产毛片av蜜桃av| 精品一区二区三区四区五区乱码| 亚洲国产欧美日韩在线播放| 中国美女看黄片| 一区二区三区乱码不卡18| 两性午夜刺激爽爽歪歪视频在线观看 | 精品一品国产午夜福利视频| 性少妇av在线| 动漫黄色视频在线观看| 亚洲激情五月婷婷啪啪| 老司机影院成人| 亚洲精品粉嫩美女一区| 成人18禁高潮啪啪吃奶动态图| 日本91视频免费播放| 一区在线观看完整版| 欧美日韩av久久| 精品久久久久久久毛片微露脸 | 国产淫语在线视频| 国产成人欧美在线观看 | 天堂俺去俺来也www色官网| 免费观看人在逋| 一级毛片女人18水好多| 国产91精品成人一区二区三区 | 色老头精品视频在线观看| 亚洲精品国产精品久久久不卡| 多毛熟女@视频| 日本91视频免费播放| 69精品国产乱码久久久| 亚洲成人免费电影在线观看| 中国美女看黄片| 免费在线观看视频国产中文字幕亚洲 | 免费久久久久久久精品成人欧美视频| 精品亚洲成a人片在线观看| 成人手机av| 欧美日韩精品网址| 国产成人精品久久二区二区91| 精品卡一卡二卡四卡免费| 啦啦啦免费观看视频1| 桃红色精品国产亚洲av| 97人妻天天添夜夜摸| 亚洲av男天堂| 韩国精品一区二区三区| 亚洲欧美激情在线| 性色av乱码一区二区三区2| 高潮久久久久久久久久久不卡| 无遮挡黄片免费观看| 波多野结衣一区麻豆| 九色亚洲精品在线播放| 美女大奶头黄色视频| 精品国产国语对白av| 国产欧美日韩精品亚洲av| 久久久久久久大尺度免费视频| 国产伦理片在线播放av一区| 亚洲免费av在线视频| 亚洲国产成人一精品久久久| 国产亚洲欧美精品永久| 伊人久久大香线蕉亚洲五| 国产精品成人在线| 亚洲中文字幕日韩| 亚洲一区二区三区欧美精品| a 毛片基地| 高潮久久久久久久久久久不卡| 国产一区有黄有色的免费视频| 99久久国产精品久久久| 麻豆av在线久日| 国产成人精品久久二区二区免费| 成人免费观看视频高清| 美女中出高潮动态图| 超色免费av| 老熟妇乱子伦视频在线观看 | 在线观看免费视频网站a站| 中文字幕人妻熟女乱码| 亚洲国产欧美日韩在线播放| 在线十欧美十亚洲十日本专区| 亚洲国产日韩一区二区| 亚洲 欧美一区二区三区| 久久亚洲国产成人精品v| 黄色 视频免费看| 超色免费av| 免费观看人在逋| 久久久久久久精品精品| 亚洲男人天堂网一区| 男女高潮啪啪啪动态图| 成年人黄色毛片网站| 一级黄色大片毛片| 美女大奶头黄色视频| 在线十欧美十亚洲十日本专区| av天堂久久9| 一区二区日韩欧美中文字幕| 2018国产大陆天天弄谢| 免费观看a级毛片全部| 国产亚洲av高清不卡| 黄色毛片三级朝国网站| 黄片小视频在线播放| 国产精品欧美亚洲77777| 日韩视频在线欧美| 欧美日韩亚洲国产一区二区在线观看 | 亚洲国产欧美日韩在线播放| 一区在线观看完整版| 动漫黄色视频在线观看| 男人操女人黄网站| 免费在线观看影片大全网站| 在线观看免费午夜福利视频| 纯流量卡能插随身wifi吗| 黄色毛片三级朝国网站| 国产一区二区激情短视频 | 国产亚洲精品久久久久5区| 99久久综合免费| 亚洲av日韩精品久久久久久密| av在线app专区| 老司机午夜十八禁免费视频| 精品人妻一区二区三区麻豆| 99热全是精品| 国产精品久久久久久人妻精品电影 | 欧美老熟妇乱子伦牲交| 丰满人妻熟妇乱又伦精品不卡| 波多野结衣一区麻豆| 热re99久久精品国产66热6| 十八禁人妻一区二区| www.av在线官网国产| 黄片播放在线免费| 免费看十八禁软件| 一区二区三区精品91| 欧美激情 高清一区二区三区| 一本—道久久a久久精品蜜桃钙片| 老熟女久久久| 久久这里只有精品19| 老汉色∧v一级毛片| 香蕉国产在线看| 69av精品久久久久久 | 欧美日韩av久久| 亚洲av欧美aⅴ国产| 下体分泌物呈黄色| 日韩免费高清中文字幕av| 99精品欧美一区二区三区四区| 久久综合国产亚洲精品| 国产在线视频一区二区| av国产精品久久久久影院| 精品国产一区二区久久| 99国产极品粉嫩在线观看| 亚洲伊人久久精品综合| 丝袜喷水一区| 欧美一级毛片孕妇| 人妻 亚洲 视频| 国产亚洲午夜精品一区二区久久| 亚洲精品一二三| 久久国产精品人妻蜜桃| av片东京热男人的天堂| 国产无遮挡羞羞视频在线观看| 又大又爽又粗| 999久久久精品免费观看国产| 老鸭窝网址在线观看| 精品人妻熟女毛片av久久网站| 正在播放国产对白刺激| 人人妻人人爽人人添夜夜欢视频| 免费在线观看日本一区| 欧美日韩中文字幕国产精品一区二区三区 | 国产成人欧美| 久久久久网色| 国产精品久久久久久人妻精品电影 | 亚洲成人免费电影在线观看| 亚洲一区中文字幕在线| 永久免费av网站大全| 欧美精品亚洲一区二区| 十八禁人妻一区二区| 一区二区三区激情视频| 精品福利观看| 亚洲一区二区三区欧美精品| 国产精品久久久久久精品古装| 午夜精品久久久久久毛片777| 亚洲专区中文字幕在线| 日韩一区二区三区影片| 亚洲精华国产精华精| 欧美成人午夜精品| 老司机亚洲免费影院| 欧美精品亚洲一区二区| 嫁个100分男人电影在线观看| 亚洲精品中文字幕一二三四区 | 国产亚洲精品第一综合不卡| 亚洲第一欧美日韩一区二区三区 | 老司机午夜福利在线观看视频 | 久久久水蜜桃国产精品网| h视频一区二区三区| av片东京热男人的天堂| 亚洲第一av免费看| 亚洲精品国产色婷婷电影| 人妻一区二区av| 美女中出高潮动态图| 777米奇影视久久| 80岁老熟妇乱子伦牲交| 两个人看的免费小视频| 日韩熟女老妇一区二区性免费视频| 午夜91福利影院| 亚洲七黄色美女视频| 亚洲午夜精品一区,二区,三区| 亚洲一区二区三区欧美精品| 12—13女人毛片做爰片一| 精品一区二区三区四区五区乱码| 久久国产精品男人的天堂亚洲| 男女国产视频网站| 国产亚洲一区二区精品| 国产精品偷伦视频观看了| 亚洲精品第二区| 中文欧美无线码| 每晚都被弄得嗷嗷叫到高潮| 老司机午夜十八禁免费视频| 男女午夜视频在线观看| 亚洲综合色网址| 中文字幕制服av| 少妇人妻久久综合中文| 日韩视频在线欧美| 成人18禁高潮啪啪吃奶动态图| 精品视频人人做人人爽| 成人影院久久| 国产在线视频一区二区| 美国免费a级毛片| 亚洲国产精品一区二区三区在线| 欧美成人午夜精品| 视频区图区小说| 亚洲国产毛片av蜜桃av| 国产人伦9x9x在线观看| 亚洲中文av在线| 美国免费a级毛片| 啪啪无遮挡十八禁网站| 建设人人有责人人尽责人人享有的| 免费观看a级毛片全部| 午夜免费成人在线视频| 亚洲精品国产一区二区精华液| 国产一卡二卡三卡精品| 一区二区三区四区激情视频| 丝袜美腿诱惑在线| 国产精品99久久99久久久不卡| 黄片大片在线免费观看| 黑人巨大精品欧美一区二区蜜桃| 人人妻人人澡人人看| 在线观看人妻少妇| 国产成人啪精品午夜网站| 深夜精品福利| 精品卡一卡二卡四卡免费| 亚洲国产精品一区二区三区在线| 建设人人有责人人尽责人人享有的| 欧美日韩福利视频一区二区| 免费少妇av软件| 亚洲欧洲精品一区二区精品久久久| 日韩,欧美,国产一区二区三区| 咕卡用的链子| 亚洲一区二区三区欧美精品| 91字幕亚洲| 成年女人毛片免费观看观看9 | 丁香六月欧美| 肉色欧美久久久久久久蜜桃| 一边摸一边做爽爽视频免费| 精品国产一区二区久久| 午夜福利乱码中文字幕| 啦啦啦中文免费视频观看日本| 香蕉丝袜av| 又紧又爽又黄一区二区| 99久久国产精品久久久| 精品一品国产午夜福利视频| 久久青草综合色| 中文字幕人妻丝袜制服| 建设人人有责人人尽责人人享有的| 亚洲一卡2卡3卡4卡5卡精品中文| 天天影视国产精品| 欧美久久黑人一区二区| 亚洲九九香蕉| 亚洲熟女毛片儿| 亚洲欧美成人综合另类久久久| 精品一区二区三卡| 午夜免费鲁丝| 51午夜福利影视在线观看| 建设人人有责人人尽责人人享有的| 黄色片一级片一级黄色片| 亚洲国产看品久久| 国产成人av激情在线播放| 叶爱在线成人免费视频播放| 午夜两性在线视频| 夜夜夜夜夜久久久久| 国产又色又爽无遮挡免| 亚洲国产精品999| 真人做人爱边吃奶动态| 啪啪无遮挡十八禁网站| 每晚都被弄得嗷嗷叫到高潮| 国产男人的电影天堂91| 十八禁网站免费在线| 欧美 亚洲 国产 日韩一| 国产黄频视频在线观看| 精品人妻1区二区| 国产精品 欧美亚洲| 国产亚洲欧美在线一区二区| 欧美日韩精品网址| 99久久国产精品久久久| 午夜福利一区二区在线看| 国产av国产精品国产| 成年美女黄网站色视频大全免费| 国产无遮挡羞羞视频在线观看| 首页视频小说图片口味搜索| 人人妻人人爽人人添夜夜欢视频| 日韩免费高清中文字幕av| 免费人妻精品一区二区三区视频| 国产深夜福利视频在线观看| 男女国产视频网站| 日韩视频一区二区在线观看| 久久久久国产精品人妻一区二区| 人人妻人人澡人人看| 人妻 亚洲 视频| 亚洲中文日韩欧美视频| 亚洲精华国产精华精| 日韩欧美国产一区二区入口| 精品一区在线观看国产| 午夜福利在线免费观看网站| 麻豆乱淫一区二区| 亚洲成国产人片在线观看| 免费在线观看完整版高清| 一本大道久久a久久精品| 超色免费av| 波多野结衣av一区二区av| 久久国产精品人妻蜜桃| 成年美女黄网站色视频大全免费| 亚洲国产欧美日韩在线播放| 亚洲精品国产一区二区精华液| 国产亚洲欧美在线一区二区| 久热爱精品视频在线9| 日本撒尿小便嘘嘘汇集6| 国产不卡av网站在线观看| 人妻人人澡人人爽人人| 亚洲色图 男人天堂 中文字幕| 欧美97在线视频| 老司机在亚洲福利影院| 人人妻人人澡人人看| 热99久久久久精品小说推荐| 一本久久精品| 制服诱惑二区| 日韩精品免费视频一区二区三区| 热re99久久国产66热| 久久精品成人免费网站| 免费黄频网站在线观看国产| 淫妇啪啪啪对白视频 | 黑人操中国人逼视频| 最新的欧美精品一区二区| 老熟女久久久| 国产精品一区二区免费欧美 | 妹子高潮喷水视频| 婷婷丁香在线五月| 国产一区二区三区综合在线观看| 97人妻天天添夜夜摸| 日本撒尿小便嘘嘘汇集6| 99精品欧美一区二区三区四区| 在线十欧美十亚洲十日本专区| 免费在线观看黄色视频的| 人妻 亚洲 视频| 搡老熟女国产l中国老女人| 制服诱惑二区| 久热这里只有精品99| 女人爽到高潮嗷嗷叫在线视频| 成人手机av| 一区福利在线观看| 91精品伊人久久大香线蕉| 午夜福利在线观看吧| 无遮挡黄片免费观看| 窝窝影院91人妻| 最新的欧美精品一区二区| 亚洲第一av免费看| 亚洲成人手机| 国产精品偷伦视频观看了| 国产淫语在线视频| 丰满少妇做爰视频| 香蕉国产在线看| 一区二区日韩欧美中文字幕| 一区二区三区乱码不卡18| 美女主播在线视频| 蜜桃在线观看..| 丰满少妇做爰视频| 久久香蕉激情| 国产av一区二区精品久久| 我要看黄色一级片免费的| 69精品国产乱码久久久| 蜜桃在线观看..| 成年人午夜在线观看视频| 精品久久久久久电影网| 捣出白浆h1v1|