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-ban d discontinuity in plasma-exposed SiGe films due to strain relaxation by a capacitance-voltage (C-V) profiling technique using metal-oxide-semiconduct or structures. Dry and wet etched samples annealed at 500, 600, 700, and 80 0 degrees C were investigated. Valence-band discontinuity Delta E-V at the Si/SiGe interface reduced with annealing temperature and completely disappe ared at higher temperature annealing. Dry etched samples demonstrated a fas ter 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 e stimate any band-gap modifications in SiGe due to process-induced damage. ( C) 1999 American Institute of Physics. [S0003-6951(99)01921-X].