Optimized Si0.5Ge0.5/Si Interface Quality by the Process of Low Energy Hydrogen Plasma Cleaning and Investigation by Positron Annihilation Spectroscopy

Positron Annihilation Spectra (PAS), Raman, and Photoluminescence spectroscopy reveal that Si0.5Ge0.5/Si interface quality can be significantly improved by the process of low energy plasma cleaning with hydrogen. In the PAS detection, the particularly small value of lifetime and intensity near the Si0.5Ge0.5/Si interface in the sample with the treatment indicate that the defect concentration is successfully reduced 2.25 times. Fewer defects existed in the interface result in the high compressive strain about 0.36% in the top epi-Si0.5Ge0.5 layer, which can be observed in the Raman spectra detection, and stronger radiative recombination rate about 1.39 times for the infrared emission, which can be observed in the photoluminescence spectra. With better interface quality, the SiGe-based devices can have better optical and electrical characteristics for more applications such as solar cells industry. The PAS is also demonstrated that it is the useful methodology tool to quantify the defect information in the SiGe-based devices.