Characterization of traps related to InAs quantum-dot growth-induced defects in GaAs by low-frequency noise measurements in reverse-biased Schottky diodes

The trap properties of Au/n-GaAs Schottky diodes, with self-organized InAs quantum dots (QDs) confined between buffer and capping GaAs layers on n+-GaAs substrates, are investigated by low-frequency noise measurements. The noise data indicate that the trap density at the interface of the buffer/capping GaAs layers is higher by about one order of magnitude than the trap density at the Au/GaAs interface. In samples with the QD-structure, deep traps are created within the buffer GaAs layer due to QD formation, with a trap density higher by about three orders of magnitude than the trap density at the Au/GaAs interface. Conduction measurements show that in Schottky diodes without QDs, the increase in the leakage current is due to an interfacial layer contributing to the barrier height lowering. In Schottky diodes comprising QDs, an anomalous leakage current is observed, attributed to local generation of deep traps due to QD formation.