Crystal phase control in self-catalyzed GaAs nanowires grown on pre-etched Si substrates

Abstract

Semiconductor nanowires play a very important role in optoelectronic devices due to their excellent photoelectric properties. However, the intermixing of zinc blende and wurtzite crystal phases limits the development of GaAs nanowires, and how to obtain pure phase GaAs nanowires has become a research hotspot. In this study, the Si substrate is pre-etched and pure ZB phase GaAs nanowires are obtained by changing the effective V/III flux ratio through the shadowing effect. A series of nanowires with different morphologies and optical properties were obtained by pre-etching the oxide layer on the Si substrate at different times. We observed that pure ZB phase GaAs nanowires with good verticality were obtained when the etching time was 3 s. The principles of crystal phase control and materials properties were discussed in detail. These results suggest that the growth method of pure phase nanowires reported herein can be applied to other low-dimensional materials, which could pave the way for future nanowire devices.