Strain relaxation of SiGe in a Si/SiGe/Si heterostructure under proton irradiation

We have studied the mechanisms underlying strained layer relaxation by means of point defect interaction. During high temperature 300 °C proton irradiation, vacancies generated in the vicinity of SiGe layer migrate and accumulate within the compressively strained SiGe layer. The accumulating vacancies are stabilized by hydrogen, which diffuses from the implanted region, thus allowing the nucleation and growth of hydrogen-vacancy V-H complexes. The formation of V-H complexes is accompanied by gradual strain relief in SiGe layer. Since the diffusion of both vacancies and hydrogen is limited by the irradiation temperature, strain relaxation of the SiGe layer is not realized during room temperature 20 °C proton irradiation. The study supports the idea that the compressive stress in the SiGe layer induces the indiffusion of vacancies and H, and reveals the important role of point defects in the strain relaxation of the strained SiGe layer.