Core-level photoelectron spectroscopy from individual heteroepitaxial nanocrystals on GaAs(001)

Abstract

Core-level spectra of individual heteroepitaxial nanocrystals were measured with a spectroscopic photoemission and low-energy electron microscope that allows laterally resolved photoemission spectroscopy. The nanocrystals were obtained by depositing nominally 2 monolayers (ML) of InAs on a Se-terminated GaAs(001) surface. The Se-termination of GaAs results in the formation of a 2--3-ML-thick film of ${\mathrm{Ga}}_{2}{\mathrm{Se}}_{3}$ on top of bulk GaAs. During heteroepitaxy the InAs reacts with the ${\mathrm{Ga}}_{2}{\mathrm{Se}}_{3}:$ A phase separation takes place on the anion sublattice, while an alloying takes place on the cation sublattice. During the initial stages of growth, a submonolayer-thick wetting layer of ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ is formed that is covered by $({\mathrm{In}}_{y}{\mathrm{Ga}}_{1\ensuremath{-}y}{)}_{2}{\mathrm{Se}}_{3}.$ $({\mathrm{In}}_{y}{\mathrm{Ga}}_{1\ensuremath{-}y}{)}_{2}{\mathrm{Se}}_{3}$-covered InAs nanocrystals are formed on this surface.