The Effect Of Ion Implantation And Annealing On The Of The Intrinsic Defects Of The Unintentionally Doped 4H-SiC

Semi-insulating silicon carbide (SiC) crystals which is one of well discussed Wide bandgap (WBG) semiconductor recent years has been considered to be used in high capacity, high frequency and thermo stable component because of its wide bandgap, high mobility and great thermal conductivity. It can be made as the substrate of the component or other material such as GaN or as the isolation between components. Up to present, there are obviously progresses about the growth of unintentionally doped 4H-SiC interiorly, in which the concentration of impurity can be decreased greatly. However, a mature has not been developed in evaluating the native defects of the 4H-SiC layers. Particularly, there are still different opinions for the native deep energy level in unintentionally doped 4H-SiC because the results obtained from measurements are different for different samples so that the origin of native deep energy level is not quit clear.This paper discussed the study of the intrinsic defects in unintentionally doped 4H-SiC prepared by LPCVD using electron paramagnetic resonance (ESR) spectroscopy. The simple had been pretreated firstly by ion implantation with Si⁺ and C⁺ then by annealing treatment.The main steps of this study are as follows. At first, the distribution of C⁺,Si⁺ into which would be implemented has been simulated by software Trim95 using Monte Carlo method. In order to avoid the intrinsic defects in deep level, SiO₂ thick in 100nm added as a mask. There kind of C⁺ ion in different low energy level, 60keV,90keV and 130keV have been implemented separately adjoined with the implementation of three kind of Si⁺ ions in low energy level, i.e., 100keV, 150keV and 200keV.Meanwhile, the whole annealing implementation process was protected by hydrogen as a cover. Time has been controlled in 10min when the heat in 1400℃and 10min and 30min in 1600℃respectively.Both annealing temperature and time have important effects on the concentration of intrinsic defects. The results showed that the ESR reached its minimum with least types and evenly distribution at 1600℃elevating anneal temperature when annealing time is 10min, which means the concentration of point defects has been decreased efficiently during the annealing treatments. After the implementation of Si⁺ anneal treated in 1600℃for 30min, both in ESR and the position of central magnetic field have been reduced. The types of intrinsic defects of 4H-SiC sample decreased along with increasing in ratio of carbon vacancy. According to the result of the study, it has been proved that the intrinsic defects in unintentionally doped 4H-SiC prepared by LPCVD have close relations between vacancy in C and vacancy in Si. The types and density of the intrinsic defects can be efficiently affected by the pretreatment of implantation with Si⁺ and C⁺ then annealing.