Terahertz emission enhancement of gallium arsenide coated with silicon nanowires
We report on the enhancement in the terahertz (THz) emission of gallium arsenide (GaAs) wafers
coated with silicon nanowires (SiNWs) and elucidate on the possible origin of the enhancement. The SiNWs were fabricated using metal-assisted chemical etching and were applied onto n-GaAs and semi-insulating (SI) GaAs using drop casting method. From standard reflection geometry THz time domain spectroscopy (THz-TDS), the THz emission was observed to have stronger enhancement for SiNW-coated SI GaAs wafers. Under different magnetic field orientations, both bare and SiNW-coated Si GaAs display π-shifted THz-TDS waveforms while bare and SiNW-coated n-GaAs display unshifted THz-TDS waveforms. The THz enhancement in the SiNW-coated wafers was attributed to the increase in photocarrier absorption induced by the SiNWs.