Deep level transient capacitance measurements of GaSb self-assembled quantum dots

Deep level transient spectroscopy (DLTS) measurements have been made on GaA s n(+)p diodes containing GaSb self-assembled quantum dots and control junc tions without dots. The self-assembled dots were formed by molecular beam e pitaxy using the Stranski-Krastanov growth mode. The dots are located in th e depletion region on the p side of the junction where they act as a potent ial well that may capture and emit holes. Spectra recorded for temperatures between 77 and 440 K reveal several peaks in diodes containing dots. A con trol sample with a GaSb wetting layer was found to contain a single broad h igh temperature peak that is similar to a line found in the GaSb quantum do t samples. No lines were found in the spectra of a control sample prepared without GaSb. DLTS profiling procedures indicate that one of the peaks is d ue to a quantum-confined energy level associated with the GaSb dots while t he others are due to defects in the GaAs around the dots. The peak identifi ed as a quantum-confined energy level shifts to higher temperatures and its intensity decreases on increasing the reverse bias. The activation energy for the quantum-confined level increases from 400 meV when measured at a lo w reverse bias to 550 meV for a large reverse bias. Lines with activation e nergies of 400, 640, and 840 meV are associated with defects in the GaAs ba sed on the bias dependence of their peak positions and amplitudes. [S0021-8 979(00)09622-5].