WO_(3)/β-Ga_(2)O_(3)异质结深紫外光电探测器的高温性能

Investigation of high-temperature performance of WO_(3)/β-Ga_(2)O_(3)heterojunction deep-ultraviolet photodetectors

得益于高达4.8 eV的禁带宽度,超宽禁带半导体氧化镓(Ga_(2)O_(3))在深紫外探测领域具有天然的优势.考虑到光电探测器在高温领域具有十分重要的用途,本文研究了一种WO_(3)/β-Ga_(2)O_(3)异质结深紫外光电探测器以及高温对其探测性能的影响.利用金属有机化学气相沉积(MOCVD)技术制备了Ga_(2)O_(3)薄膜,并采用旋涂和磁控溅射技术分别制备了WO_(3)薄膜和Ti/Au欧姆电极.在室温(300 K)下,该探测器的光暗电流比为3.05×10^(6),响应度为2.7 mA/W,探测度为1.51×10^(13)Jones,外量子效率为1.32%.随着温度的升高,器件的暗电流增加、光电流减少,导致上述光电探测性能的下降.为了理清高温环境下探测性能退化的内在物理机制,研究了温度对光生载流子产生-复合过程的影响,继而阐明了高温对光电流增益机制的影响.研究发现,WO_(3)/β-Ga_(2)O_(3)异质结光电探测器能够在450 K的高温环境中实现稳定的自供电工作,表明全氧化物异质结探测器在恶劣探测环境中具有应用潜力.

Owing to the high bandgap of up to 4.8 eV,Ga_(2)O_(3)has a natural advantage in the field of deep-ultraviolet(DUV)detection.The Ga_(2)O_(3)-based photoconductors,Schottky and heterojunction detectors are proposed and show excellent photodetection performance.The Ga_(2)O_(3)heterojunction detectors are self-driven and feature low power consumption.On the other hand,considering the ultra-wide bandgap and low intrinsic carrier concentration,Ga_(2)O_(3)-based photodetectors are exhibiting important applications in high-temperature photodetection.In this work,a WO_(3)/β-Ga_(2)O_(3)heterojunction DUV photodetector is constructed and the effect of high temperature on its detection performance is investigated.The β-Ga_(2)O_(3)films are prepared by metal-organic chemical vapor deposition(MOCVD),and WO_(3) films and Ti/Au ohmic electrodes are prepared by spin-coating technology and magnetron sputtering technique,respectively.The current-voltage(I-V)and current-time(I-t)measurements are performed at different ambient temperatures.Parameters including light-dark-current ratio(PDCR),responsivity(R),detectivity(D*),and external quantum efficiency(EQE)are extracted to evaluate the deep-ultraviolet detection performance and its high-temperature stability.At room temperature(300 K),the PDCR,the R,the D*,and the EQE of the detector are 3.05×10^(6),2.7 mA/W,1.51×10^(13)Jones,and 1.32%,respectively.As the temperature increases,the dark current of the device increases and the photocurrent decreases,resulting in the degradation of the photodetection performance.To explore the physical mechanism behind the degradation of the detection performance,the effect of temperature on the carrier generation-combination process is investigated.It is found that the Shockley-Read-Hall(SRH)generation-combination mechanism is enhanced with the increase of temperature.Recombination centers are introduced from the crystal defects and interfacial defects,which originate mainly from the SRH process.Specifically,the dark current comes mainly from the depletion region of WO_(3)/β-Ga_(2)O_(3),and the carrier generation rate in the depletion region is enhanced with temperature increasing,which leads to the rise of dark current.Similarly,the increase of temperature leads to the improvement of the recombination process,therefore the photocurrent decreases at a higher temperature.This effect can also well explain the variation of response time at a high temperature.Overall,it is exhibited that the WO_(3)/β-Ga_(2)O_(3)heterojunction photodetector can achieve stable self-powered operation even at an ambient temperature of 450 K,indicating that the all-oxide heterojunction detector has potential applications in harsh detection environments.