Effects of substrate material on the electrical properties of self-assembled InAs quantum dots-based laser structures

In this work, the effects of the substrate material on the electrical properties of self-assembled InAs quantum dots (QDs)-based laser structures have been reported. Two InAs QD laser structures with the same active regions deposited on GaAs and Si substrates utilizing strain reducing layer (SRL) containing GaAs/InGaAs have been investigated using current–voltage ( I – V ), capacitance–voltage, and Deep-Level Transient Spectroscopy (DLTS) techniques. The I – V measurements illustrated that the rectification ratio ( I F / I R ) and built-in potential ( ϕ B ) for the sample deposited on Si substrate are higher than that of sample deposited on GaAs substrate. However, the series resistance (Rs) of the InAs QDs deposited on Si substrate is lower than that of the InAs QDs deposited on GaAs substrate. The DLTS and Laplace-DLTS measurements showed that the number of traps in InAs QDs/GaAs devices is lower than that in InAs QDs/Si devices, corroborating with I – V results.