Growth and surface passivation of near-surface InGaAs quantum wells

The growth and surface passivation of near-surface InGaAs quantum wells (QWs) on GaAs (1 1 0) substrate have been investigated. Triangular shaped small islands, approximate areal density of 10 cm , are observed on metal organic vapor phase epitaxially grown GaAs single layer and InGaAs multi-quantum wells (MQWs) surfaces in a wide range of growth temperatures. By optimizing the growth conditions, high quality In0:22Ga0:78As QWs with optical properties comparable to the same structure grown on GaAs (1 0 0) are obtained. Near-surface single QWs are used to study the surface passivation. Epitaxially in situ grown mono-layer thick GaP and InP layers as well as surface phosphorization with tertiarybutylphosphine (TBP) are utilized as passivation methods. Passivation significantly increases photoluminescence (PL) intensity and carrier lifetime of near-surface QWs. The best passivation efficiency is obtained by surface phosphorization with TBP on (1 1 0)-oriented near-surface QW while the ultra-thin InP layer is the best on (1 0 0)-oriented nearsurface QW. After 7 months of air exposure, all passivated near-surface QWs still show high PL intensity comparable to deep QW while the PL intensity of unpassivated samples degraded severely. Also, the differences between the optical properties of QWs on GaAs (1 1 0) and (1 0 0) substrates are observed and discussed. r 2007 Elsevier B.V. All rights reserved. PACS: 81.65.Rv; 68.55.Jk; 68.65.Fg; 81.07.St; 81.15.Gh