Room-temperature photoluminescence in GaAsSb nanowires under high-pressure

Abstract

Ternary GaAsSb nanowires (NWs) have considerable potential applications in infrared optical nanodevices due to their direct bandgap and wavelength-tunable light emission which covers the range from 870 nm to 1700 nm by changing the content of Sb in GaAsSb NWs. Due to the high surface state density, the light emission efficiency of GaAsSb NWs is quite low and the light emission is difficult to observe under room-temperature conditions. Previous studies on the optical properties of GaAsSb NWs were mainly carried out under low-temperature conditions, thereby limiting their room-temperature optical properties modulation research and room-temperature applications. In the present study, we modulate the optical properties of GaAsSb NWs under room-temperature conditions through the high-pressure strategy, by means of both photoluminescence (PL) and Raman spectroscopy. With the increase of pressure, the PL intensity of GaAsSb NWs is obviously enhanced at room temperature and the PL peak position shows a blue-shifted trend. With the change of wavelength (473 nm, 514 nm, and 633 nm) of the incident laser, the excitation-wavelength-dependent PL can be observed in GaAsSb NWs. The laser with a longer wavelength (633 nm) will excite the stronger light emission. The Raman spectra of GaAsSb NWs excited by different lasers (473 nm, 514 nm, and 633 nm) all show blue shift under compression. We select four pressure points (0.7 GPa, 1.2 GPa, 1.8 GPa, and 2.5 GPa) for the detailed comparison between the Raman spectra excited by different lasers. Under the excitation of 473 nm laser, the Raman peaks of GaAsSb NWs show an evident red-shift compared with those excited by 514 nm or 633 nm laser, which reveals the existence of temperature difference. The estimated relative temperature difference in GaAsSb NWs induced by two different lasers (473 nm and 633 nm) can reach up to 200 K. The laser with shorter wavelength will induce a stronger heating effect in GaAsSb NWs and reduce the light-emission efficiency. Under high-pressure condition, the charge transfer between the surface of GaAsSb NWs and pressure transmitting medium can be enhanced, which resulting in the reduction of surface state density and laser-heating effect. Therefore, the high-pressure strategy provides an efficient route for suppressing the high surface state density and optimizing optical properties of semiconductor nanostructures.