Electrical characterization of Si/Si_1-xGe_x/Si quantum well heterostructures using a MOS capacitor

Ultra-thin oxides (<100 angstroms) have been grown on strained Si/Si_1-xGe_x/Si layers at a low temperature using microwave O₂- and NO-plasma. Metal-oxide-semiconductor (MOS) capacitors fabricated using these oxides have been used for the determination of the hole density in the Si-cap and the Si_0.8Ge_0.2-channel. The valence band discontinuity (ΔE_v) at the Si/Si_0.8Ge_0.2 heterointerface has been extracted from the carrier confinement characteristics of the quantum well. Capacitance-voltage (C-V) profiling has been used to measure the apparent doping profile and thickness of the unconsumed Si-cap layer. Fowler-Nordheim (F-N) constant current stressing shows that NO-plasma grown oxides have an improved charge trapping behavior over the O₂-plasma grown oxides.