Characterization And Analysis Of Defects Induced By Electron Irradiation In GaN-based Devices

Gallium nitride(GaN),as the frontier and hotspot of semiconductor research in the world.Its application fields are constantly expanding.With the development of applications,more and more GaN devices will work in the irradiated environment.The radiation particles in the irradiated environment will induce various defects in GaN devices,which will affect the performance of GaN devices.Therefore,the effective characterization of radiation-induced defects in GaN devices has important theoretical significance and practical value for the application of GaN devices in irradiated environment.In this thesis,GaN-based light-emitting diodes(LED)and AlGaN/GaN heterojunctions were irradiated by 1.5 MeV electron beams at doses of 1 kGy,10 kGy and 50 kGy respectively.Then the defects induced by different doses of electron irradiation were characterized and analyzed by frequency conversion C-V test,low-frequency noise test,photoluminescence spectrum(PL),time-resolved photoluminescence spectrum(TRPL),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).The main research work and results are as follows:1?Variable frequency C-V test and low frequency noise test,PL spectrum,TRPL spectrum and XRD test were carried out for GaN-based LED irradiated by different doses of electrons.Variable frequency C-V test results show that electron irradiation causes compound center point defects and interface state defects in the device,and the defect density increases with the increase of irradiation dose.Low-frequency noise measurements show that electron irradiation produces a large number of interface defects in the active region of the device,and the defect density increases with the increase of irradiation dose.PL spectra showed that telectron irradiation causes N vacancy?MgGa substitution and MgGa-VN complex.The radiation recombination center in the sample increases with the increase of irradiation dose,and the non-radiation recombination center produced when the irradiation dose is 50 kGy decreases the luminous intensity of the LED.The results of TRPL spectra show that the concentration of unbalanced carriers,the density of radiation recombination centers and non-radiation recombination centers increase with the increase of irradiation dose.XRD results show that electron irradiation increases the defect density,and VN or VGa vacancy defects and MgGa substitution defects occur in the samples.2?AlGaN/GaN heterojunction epitaxial wafers irradiated by different doses of electrons were tested by variable frequency C-V,XRD and XPS.Variable frequency C-V measurements show that electron irradiation causes Ga acceptor defects in the AlGaN/GaN heterojunction,and interface defects on the surface and interface of the heterojunction.The density of Ga acceptor defects,surface defects and interface defects increases with the increase of irradiation dose.XRD test results show that VN and VGa vacancy defects and GaAl substitution defects are produced in AlGaN/GaN heterojunctions by electron irradiation,and the defect density increases with the increase of irradiation dose.XPS test results show that electron irradiation decreases Al2O3 and increases Ga2O3 on the surface of heterojunction due to Al-O bond breaking.At the same time,irradiation causes Ga and N vacancies on the surface of heteroj unction,and the vacancy density increases with the increase of irradiation dose.Through the study of this thesis,we can combine the change of device performance caused by electronic irradiation with the defect induced by irradiation,and provide reference value for the application of electronic irradiation in device mocdification.