Study On The Structural And Photoelectric Properties Of Si Doped GaAs Under Irradiation

Gallium Arsenide?GaAs?,as a semiconductor material with high electron mobility and wide band gap,has incomparable advantages in the preparation of laser,photodiode,LED and other optoelectronic devices.The GaAs also has a strong radiation resistance,so it is often used to make aerospace devices and nuclear reactor detectors.During the space missions or nuclear application,the devices will be exposed to radiation environment,such as gamma rays,high-energy electrons,proton and ions,which probably cause the creation of defect clusters and dislocations so that the photoelectric properties of devices will be influenced.Therefore,the study of irradiation effect of GaAs on its structural and optical properties is of great significance to the prediction of irradiation behavior of materials and the development of radiation resistant devices of GaAs.The main work of this paper is as follows:1.The structural and photoelectric characteristics of Si-doped GaAs at different Gamma irradiation doses?0,0.1,1 and 10 KGy?are studied.The AFM image characterization shows that at low irradiation dose the surface roughness of the sample is in the order of 10^-11 nm,and the transverse scan line affected by noise appears in the image,indicating that the surface is still compact and smooth at this dose.With the increase of irradiation dose,the grain size on the surface becomes larger,and more uneven voids appear.The roughness of the silicon-doped gallium arsenide thin film increases with the increasing radiation dose,while Raman scattering analysis indicates that the average strain is 0.009 under 10 KGy,less than the maximum non-relaxation strain of GaAs?0.038?,indicating that it still has good crystallinity.In addition,the current of Si-doped GaAs decreases significantly under 3 V bias,while its luminous intensity is increased by about 60%under 10 KGy gamma radiation,indicating that the gamma radiation dose may contribute to the removal of the non-radiative recombination center of the GaAs layer.These results suggest that the Si-doped GaAs samples still maintain good crystallinity under Gamma irradiation with high dose,and their luminescence performance is improved significantly.2.The structural and photoelectric characteristics of Si-doped GaAs irradiated by N and Ar ions are studied.The irradiation dose is 0,10¹⁵ and 10¹⁶ ion/cm^-2.It is shown that the Ar⁺ion irradiation has little damage to the GaAs surface.For the irradiation dose of5×10¹6cm^-2,the RMS roughness is 0.547 nm,indicating that the surface is still compact and smooth.After N⁺ion irradiation,the GaAs surface roughness is increased sharply to25.9 nm,meaning that the surface is significantly damaged.At a dose of 5×10¹⁶ cm^-2,the GaAs strains of N⁺and Ar⁺ion irradiation are 0.075 and 0.028,respectively.Relative to the maximum non-relaxation strain of GaAs?0.038?,a strain of 0.075 means that the structure has been amorphous under the N⁺irradiation.When the irradiation dose is greater than 5×10¹⁵ cm^-2,the photoluminescence spectrum is quenched,i.e.,both N⁺and Ar⁺ions significantly reduce the luminous efficiency of GaAs because of the enchancement of nonradiative recombination after ion irradiation.To summarize,the structural and photoelectric characteristics of Si doped GaAs after N⁺ion,Ar⁺ion and Gamma irradiation are systematically studied.As compared with Gamma irradiation,N⁺and Ar⁺ion irradiation at doses of 5×10¹⁶ cm^-2 result in greater lattice strain in Si-doped GaAs.At the Gamma dose of 10 KGy,the luminescence performance of GaAs iss greatly improved due to the removal of the non-radiative recombination center.However,when the ion irradiation dose is higher than 5×10¹⁵ cm^-2,the photoluminescence spectrum of GaAs is quenched.