Novel method of determining conduction-band discontinuities by using monolayer energy splitting in quantum-well structures

Abstract

We propose a novel method of determining conduction-band discontinuities ΔEc by using the relationship between the splitting energy ΔE due to monolayer fluctuation and quantum energy shift Eq in single-quantum-well (SQW) structures. This evaluation method is described by differentiating the eigenvalue equation for a finite square quantum well. The obtained formula indicates that ΔE is approximately proportional to E3/2q and that this evaluation technique is independent of ambiguity in estimation of well thickness. We apply this method to an InGaAs/InP SQW system. 4.2-K photoluminescence spectra of InGaAs/InP SQWs grown by low-pressure metalorganic chemical vapor deposition show clearly resolved doublets and in some cases triplets caused by monolayer fluctuations. As a result, we found that ΔEc =(0.25–0.30)ΔEg gave the best fit for the InGaAs/InP heterointerface.