Semiconductor-metal transition in GaAs nanowires under high pressure

We investigate the structural phase transitions and electronic properties of GaAs nanowires under high pressure by using synchrotron x-ray diffraction and infrared reflectance spectroscopy methods up to 26.2 GPa at room temperature. The zinc-blende to orthorhombic phase transition was observed at around 20.0 GPa. In the same pressure range, pressure-induced metallization of GaAs nanowires was confirmed by infrared reflectance spectra. The metallization originates from the zinc-blende to orthorhombic phase transition. Decompression results demonstrated that the phase transition from zinc-blende to orthorhombic and the pressure-induced metallization are reversible. Compared to bulk materials, GaAs nanowires show larger bulk modulus and enhanced transition pressure due to the size effects and high surface energy.