Photoluminescence from InAs Quantum Dots Buried Under Low‐Temperature‐Grown GaAs

Abstract

Optical and structural study of a system of InAs quantum dots (QDs) buried under low‐temperature (LT) grown GaAs layers with different buffer layers in between has been performed. It has been shown that the buffer is very important for both atomic structure and electronic processes. The direct overgrowth at low temperature causes the formation of misfit dislocation and related drop of the photoluminescence (PL) intensity from the InAs QDs. The defect formation is eliminated by using either 5 nm thick GaAs or combined AlAs/GaAs buffer. Strong changes in the QD‐related PL intensity and line shape are experimentally revealed in the case of thin GaAs buffer. These changes are quantitatively described in terms of electron tunneling from the InAs QDs through the GaAs barrier to the continuum of states in the LT‐GaAs. When a 2.5 nm thick portion of the GaAs buffer is substituted by AlAs, the barrier becomes nontransparent for the electron tunneling from the ground states in the InAs QDs. As a result, the QD‐related PL becomes much stronger and the line shape becomes similar to that from the reference sample in the photon energy range of ground state transitions.