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.

Impact of Built‐In Electric Field on the Emission Characteristics of InAs/GaAs Quantum Dot Laser Structure

“…During the last three decades, substantial investigations have been made by researchers worldwide for studying InAs/GaAs QDs and their dynamical behavior in different temperature regimes under various experimental conditions. [ 12–14 ] Insight into luminescence studies over different temperature regimes is essential to realize high‐performance QD lasers operating at room temperature. Surface photovoltage spectroscopy (SPS) is another complementary technique to investigate various electronic transitions, including those that do not generally appear in PL measurements.…”