Strong sulfur passivation effects on the gas sensitivity of an In0.3Ga0.7As surface quantum dots coupling structure

Abstract The strong sulfur passivation effects on the gas sensitivity of a coupling structure is investigated. The coupling structure is consisted of an In0.3Ga0.7As surface quantum dots (SQDs) layer being stacked on 5-layers buried quantum dots (BQDs) and is grown by solid source molecular beam epitaxy. With the increase of sulfur passivation time, both the height of SQDs and the gas response of the coupling structure are significantly reduced. Simultaneously, the PL emission from SQDs is suppressed deeply and the decay time of carriers in BQDs layers are risen evidently. After 20mintues passivation, the gas response is reduced to one fourth of that of un-passivated sample, the decay time of carriers in BQDs layers rose from 134 ps to 181 ps and the PL emission from SQDs almost disappeared. This work is an important meaning for the development of high stability and repeatability gas sensors