InGaAs quantum dots grown with GaP strain compensation layers

Abstract

A major obstacle in the growth of stacked dot structures with a large number of layers is the high degree of strain in the dot layers. Strain buildup can affect the nucleation of the dots, which may cause defects that are detrimental to device performance. In this work, thin GaP layers are inserted below the quantum dot (QD) layer in single and stacked In0.5Ga0.5As/GaAs QD structures. These layers counterbalance the strain caused by the previous layers. Changes in dot nucleation are observed for dots grown directly on GaP layers. The QDs are found to be smaller in width and height. The luminescence from these dots is blueshifted due to interdiffusion between the dots and the GaP buffer layer. In a single layer of dots, no change in dot formation is seen when a thin GaAs barrier layer is deposited between the GaP layer and the QD layer. However, in stacked structures, the addition of a GaP layer below each QD layer is found to increase the density of the dots in the top layer of the stack. The room-temperature photoluminescence intensity is also increased.