Plasma process-induced band-gap modifications of a strained SiGe heterostructure

Exposure to plasma etching and subsequent annealing can relax the strain of coherently strained SiGe. This work investigates the change in valence-band discontinuity in plasma-exposed SiGe films due to strain relaxation by a capacitance–voltage (C–V) profiling technique using metal–oxide–semiconductor structures. Dry and wet etched samples annealed at 500, 600, 700, and 800 °C were investigated. Valence-band discontinuity ΔEV at the Si/SiGe interface reduced with annealing temperature and completely disappeared at higher temperature annealing. Dry etched samples demonstrated a faster relaxation mechanism as compared to their wet etched counterparts. The C–V method has turned out to be a simple, fast, and efficient approach to estimate any band-gap modifications in SiGe due to process-induced damage.