Effect of rapid thermal annealing on the noise properties of InAs/GaAs quantum dot structures

Abstract

Self-assembled InAs quantum dots (QDs) were grown by molecular beam epitaxy (MBE) on n(+)-GaAs substrates, capped between 0.4 mu m thick n-type GaAs layers with electron concentration of 1x10(16) cm(-3). The effect of rapid thermal annealing at 700 degrees C for 60 s on the noise properties of the structure has been investigated using Au/n-GaAs Schottky diodes as test devices. In the reference sample without containing QDs, the noise spectra show a generation-recombination (g-r) noise behavior due to a discrete energy level located about 0.51 eV below the conduction band edge. This trap is ascribed to the M4 (or EL3) trap in GaAs MBE layers, related to a chemical impurity-native defect complex. In the structure with embedded QDs, the observed g-r noise spectra are due to a midgap trap level ascribed to the EL2 trap in GaAs, which is related to the InAs QDs dissolution due to the thermal treatment. (C) 2007 American Institute of Physics.