The photo-carrier density in the depletion region of the GaN-based p-i-n ultraviolet(UV) detector is calculated by solving the photo-carrier continuity equation,and the photo-carrier screening electric field is calcul...The photo-carrier density in the depletion region of the GaN-based p-i-n ultraviolet(UV) detector is calculated by solving the photo-carrier continuity equation,and the photo-carrier screening electric field is calculated according to Poisson's equation.Using the numerical calculation method,a novel model of photo-carrier screening effect is presented.Then the influence of photo-carrier screening effect on the distribution of photo-carrier density in the depletion region of p-i-n detector is discussed.The influence of incident power,bias voltage and carrier life time on the photo-carrier screening effect is also analyzed.It is concluded that the influence of photo-carrier screening effect on the performance of GaN-based p-i-n UV detector is non-monotone,the maximum of carrier drift velocity and the minimum of response time can be realized by adjusting the applied voltage.Besides,the incident light duration has strong impact on the photo-carrier screening effect.展开更多
Transient photovoltage(PV) technique was applied to investigate the separation and the transport mechanism of the photo-induced charge carriers on nano-TiO_ 2 film electrode. The positive PV transients were observed w...Transient photovoltage(PV) technique was applied to investigate the separation and the transport mechanism of the photo-induced charge carriers on nano-TiO_ 2 film electrode. The positive PV transients were observed whenever the light was incident from the gauze platinum(top illumination) or the ITO electrode(bottom illumination). This implies that the photo-induced electrons always accumulate near the ITO. Simultaneously, it is found that under the singe pulse illumination, PV transient at bottom illumination needs a shorter time to reach its maximum than that at top illumination. This indicates that the photo-induced carriers are separated faster on TiO_ 2/ITO interface than that in the bulk of the TiO_ 2 film. These demonstrate the existence of the contact potential on the TiO_ 2/ITO interface, with the downward band bending from the TiO_ 2 to ITO, which may cause the excess carriers to be separated by drift. Under the repeated pulses illumination, the PV transients at top illumination remained unchanged, while those at bottom illumination changed significantly. This results from the trapping of the excess electrons on the TiO_ 2/ITO interface.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 60976068 and 60936005)the Cultivation Fund of the Key Scientific and Technical Innovation Projectthe Ministry of Education of China Program (Grant No. 708083)
文摘The photo-carrier density in the depletion region of the GaN-based p-i-n ultraviolet(UV) detector is calculated by solving the photo-carrier continuity equation,and the photo-carrier screening electric field is calculated according to Poisson's equation.Using the numerical calculation method,a novel model of photo-carrier screening effect is presented.Then the influence of photo-carrier screening effect on the distribution of photo-carrier density in the depletion region of p-i-n detector is discussed.The influence of incident power,bias voltage and carrier life time on the photo-carrier screening effect is also analyzed.It is concluded that the influence of photo-carrier screening effect on the performance of GaN-based p-i-n UV detector is non-monotone,the maximum of carrier drift velocity and the minimum of response time can be realized by adjusting the applied voltage.Besides,the incident light duration has strong impact on the photo-carrier screening effect.
文摘采用三电极体系在硫酸铜-乳酸体系中电化学沉积法制备Cl∶Cu_2O薄膜,通过光电流(I-t)测试、莫特-肖特基(M-s)曲线测试、光电压衰减测试(V-t),研究Cl离子掺杂对氧化亚铜薄膜性能产生的影响。结果表明当p H值为8.5时,可以获得n型氧化亚铜。随着CuCl_2的加入,氧化亚铜薄膜的光电流密度先上升后下降。莫特-肖特基曲线测试的载流子浓度与光电流密度的趋势一致,当Cu Cl2为40 mmol/L时达到最高值,光电流密度为0.11 m A/cm2(较纯氧化亚铜提高了247.6%),载流子浓度为3.58×10^(19)cm^(-3)(较纯氧化亚铜的载流子浓度提高了2457%)。将光电压衰减测试结果进行拟合后发现在40 mmol/L Cu Cl_2溶液中得到的薄膜,其载流子的半衰期提高到了8.92 s,说明较纯氧化亚铜薄膜的光稳定性大大提高了。
文摘Transient photovoltage(PV) technique was applied to investigate the separation and the transport mechanism of the photo-induced charge carriers on nano-TiO_ 2 film electrode. The positive PV transients were observed whenever the light was incident from the gauze platinum(top illumination) or the ITO electrode(bottom illumination). This implies that the photo-induced electrons always accumulate near the ITO. Simultaneously, it is found that under the singe pulse illumination, PV transient at bottom illumination needs a shorter time to reach its maximum than that at top illumination. This indicates that the photo-induced carriers are separated faster on TiO_ 2/ITO interface than that in the bulk of the TiO_ 2 film. These demonstrate the existence of the contact potential on the TiO_ 2/ITO interface, with the downward band bending from the TiO_ 2 to ITO, which may cause the excess carriers to be separated by drift. Under the repeated pulses illumination, the PV transients at top illumination remained unchanged, while those at bottom illumination changed significantly. This results from the trapping of the excess electrons on the TiO_ 2/ITO interface.
