Raman Study Of Heavy-ion Irradiated In_xGa_1-xN（0.32 ≤ X ≤ 1.0）films

InxGa1-xN is one of the most important group-III-nitride semiconductor materials. The band gap of InxGa1-xN varies between 0.77 eV(x = 1)and 3.42 eV(x = 0), which covers nearly the whole solar spectrum, consequently it has been widely used for the fabrication of electronic and optoelectronic devices. Ion implantation techniques may be of importance to modification, especially to p-type doping of InxGa1-xN materials. However, ion implantation inevitably introduces radiation damage in materials, so the study of radiation damage is crucial for the application of ion-implancation techniques. As compared to GaN, there have been relatively few reports on radiation effects in InxGa1-xN, particularly in high In-content InxGa1-xN(x > 0.2)to date. The radiation damage processes in Inx Ga1-xN have not been well understood. In this work, wurzite InxGa1-xN(0.32 ≤ x ≤ 1.0)films were irradiated with 5 MeV Xe and 4 Me V Kr ions at room temperature to ion fluences from 3×1011 to 6×1013 ions/cm2. After ion irradiations, the structural and electronical changes in the films were investigated by Raman spectroscopy.The results of the Raman data show that:1)with increasing ion fluences, the full width at half maximum of E2(high)and A1(LO)peaks increase, and the intensities of the disordering peaks, such as A1(TO)and E1(LO)peaks, gradually increase. Dr being calculated by the intensity ratio of E1(LO)and A1(LO)peaks are used to evaluate the relative disorder of the films. It is found that the Dr values for InxGa1-xN with x > 0.7 are significantly higher than those for Inx Ga1-xN with the lower In concentrations, clearly suggesting that radiation resistance of InxGa1-xN decreases with increasing In concentration in InxGa1-xN, which is attributed to the reduced dynamic annealing efficiency of radiation defects in InxGa1-xN with the higher In concentrations. 2)the peak position of A1(LO)peak shifts obviously towards lower-frequencies after ion irradiations, indicating the decrease of carrier concentration in the irradiated films. 3)At the same radiation damage dose(dpa), the Dr values for the Xe-irradiated InxGa1-xN are larger than those for the Kr-irradiated InxGa1-xN, suggesting that the Xe ion irradiation produces more significant structrual damage in the films than the Kr ion irradiaiton. This is owing to the higher defect density in collision cascade in the films induced by the heavier Xe ions.In conclusion, significant structural damage and decrease of carrier concentration are induced in InxGa1-xN(0.32 ≤ x ≤ 1.0)films irradiated with the Xe and Kr ions at room temperature to low ion fluences(≤ 6×1013 ions/cm2). Further studies of irradiation behavior in InxGa1-xN at elevated temperatures are needed to apply ion-implantation techniques in the materials.