Buffer optimization for InP-on-Si [001] quasi-substrates

Different types of InGaAs/InP(InAlAs) superlattice structures and low temperature grown single InAlAs layers are examined with respect to the defect reduction and improvement of the surface roughness of InP-on-Si [001] quasi-substrates. By using an InAlAs layer grown at optimized conditions a surface roughness of 1.9 nm and a good crystal quality are achieved. Resonant-tunneling diodes fabricated on top of the improved quasi-substrate exhibit a peak-to-valley-ratio of 2 and a peak current density of 27 kA/cm at room temperature showing the high application potential of this approach.