Atomic-scale observation of interfacial roughness and As–P exchange in InGaAs/InP multiple quantum wells

Abstract

Cross-sectional scanning tunneling microscopy (XSTM) has been used to study interfacial properties of InP-on-InGaAs interfaces in InGaAs/InP multiple quantum wells grown by metalorganic vapor phase epitaxy with a growth interruption. XSTM has enabled us to separately identify step-like roughness and distributions of As atoms incorporated in the InP layer near the interface. The As composition profile along the growth direction analyzed from distributions of As atoms in XSTM images shows an exponential variation with distance from the InP-on-InGaAs interface. It is found that the growth interruption of 30 s reduces considerably the roughness amplitude to 0.45 nm from 1.1 nm and increases the coherent length from 22 to 27 nm.