The effect of silicon films impurity compensation on the performance of silicon drift detector

Abstract

Silicon drift detector (SDD) fabricated using in-situ doping technology has been developed in recent years since its advantages of low process temperature and ultra-shallow junction. However, the N+ and P+ regions on the same substrate surface cannot be formed simultaneously during the process of fabricating SDD by using in-situ doping. To overcome these challenges, we proposed a simple method to form stacked silicon films with phosphorus doped layer and boron doped layer on the same surface of SDD by impurity compensation effect in this work. The stacked silicon films with thicker boron doped layer (stack-1, partially compensated) and thinner boron doped layer (stack-2, totally compensated) were prepared by impurity compensation. Then we further investigated the films properties and electrical properties of stack-1 and stack-2. The experimental results showed that the leakage current of stack-1 was larger than that of stack-2 in PN junction devices. The simulation results indicated that a tunnel junction was formed in the stack-1 which would cause a very large leakage current when a reverse bias was applied to the PN junction. Finally, stack-2 with completely compensated boron doped layer was used to fabricated SDD and the best energy resolution achieved at the temperature of 213 K was 180 eV @ the Mn-Kα line (5.9 keV). The good energy resolution of this SDD indicated that the stacked silicon films with fully compensated boron doped layer are suitable applied to fabricating the silicon drift detectors and can also obtain excellent device performance.