The Fabrication And Study Of GaN-Based HEMT With 2DEG Controlled By Photosensitive Gate

The high-dimensional electron gas(2DEG)concentration at the AlGaN/GaN heterojunction interface of the GaN-based HEMT is susceptible to the control of the surface state.The GaN-based HEMT integrated functional film affects the surface state charge to control the 2DEG and achieve specific detection,it is one of the important research directions in the current detector field.The film(PZT)has excellent pyroelectric effect/PV effect,which is an important functional photographic material in the field of infrared-UV detector research.The new detection mechanism is proposed through the introduction of the grid-control principle of the HEMT,the structure of the GaN-based HEMT device with photosensitive gate,PZT thin films are prepared on GaN-based HEMT as the photosensitive gate,the channel current is changed by the voltage generated by PZT pyroelectric/photovoltaic effect to achieve the detection of optical radiation.The main study is the photodetection structure of GaN-based HEMT with photosensitive gate and its related preparation technology.Firstly,we focus on the preparation and performance of the key sensitive element(the photosensitive gate PZT).a)Using RF magnetron sputtering method,the effects of different sputtering power and pressure on the sputtering thickness of the film were designed;The growth and crystallization of PZT on the bottom electrodes of different metals were studied and the Ti/Pt were used as the bottom electrode to obtain the best surface morphology;b)The microstructures of PZT films with different thickness were studied by XRD,FIB and SEM,and the"cracks"and"grain"were found in the analysis of stress release through the annealing process.c)The electrical properties of PZT of different bottom electrode and thickness were studied by using ferroelectric test system:Ti/Pt as the lower electrode to get better ferroelectric and leakage current,the 2h film has the greater residual polarization intensity of 20 uC/cm~2 and the maximum polarization intensity of 65 uC/cm~2;d)The optical properties of different thickness PZT were studied by using a spectrophotometer:the light absorption rate of the film at the wavelength of<400 nm is very high,and the light absorption characteristic of the thick film pair>1500 nm wavelength is enhanced.Secondly,the photosensitive gate layout was designed to determine the purpose of the each device.The fabrications of GaN-based HEMT devices with photosensitive gate of the silicon and sapphire substrates were studied.The process parameters were optimized and and the process conditions of the photosensitive gate were determined.Finally,using the Keithley 4200,the GaN-based HEMT device samples with/without photosensitive gate of the silicon and the sapphire substrates were applied to scan voltage Vds of 0-15V and Vgs voltage of-3V,-2.5V,-2V,0V,0.5V,using the current output characteristic curve to show the final result,a)in the test of visible/UV light,the sapphire substrate HEMT device with photosensitive gate significantly improved the current curve existing"cross"phenomenon,and the emergence of current collapse is more obvious;And there is no obvious difference and decrease between the HEMT device with/without photosensitive gate of the silicon substrate;b)in the test of thermal radiation,for HEMT devices with photosensitive gate of the sapphire substrate,the increase of the Ids is significantly different from the descent phenomenon of the Ids without photosensitive gate;For the HEMT device with photosensitive gate of the silicon substrate,it exhibits a"cross"phenomenon compared to the output current curve of the device without photosensitive gate and the dark field;In summary,the photosensitive gate PZT has a role in the HEMT devices of the silicon and sapphire substrates under visible light,UV light and thermal radiation.