Atomic structure and optical properties of InAs submonolayer depositions in GaAs

Abstract

Using cross-sectional scanning tunneling microscopy and photoluminescence spectroscopy, the atomic structure and optical properties of submonolayer depositions of InAs in GaAs are studied. The submonolayer depositions are formed by a cycled deposition of 0.5 monolayers InAs with GaAs spacer layers of different thicknesses between 1.5 and 32 monolayers. The microscopy images exhibit InAs-rich agglomerations with widths around 5 nm and heights of up to 8 monolayers. A lateral agglomeration density in the 1012 cm−2 range is found. During the capping of the InAs depositions a vertical segregation occurs, for which a segregation coefficient of ∼0.73 was determined. In the case of thin GaAs spacer layers, the observed segregation forms vertically connected agglomerations. The photoluminescence spectra exhibit peaks with linewidths below 10 meV and show a considerable dependence of the peak energy on the spacer thickness, even up to 32 monolayers GaAs, indicating a long range electronic coupling.