The effect of deposition time on the structural and optical properties of β-Ga2O3 nanowires grown using CVD technique

In the present work, we have investigated the effect of deposition time on the morphological, structural, and photoluminescence (PL) properties of beta-Ga2O3 NWs grown by CVD technique. The diameter and length of the as-grown NWs varied for the deposition time of 1-4 h, from 50 to 100 nm and 5-15 mu m, respectively. The crystalline quality of the NWs improved with increasing the deposition time. The detailed transmission electron microscopy (TEM) and fast Fourier Transformation (FFT) measurements revealed that the as-grown beta-Ga2O3 NWs were single crystalline. Furthermore, we have studied the variation of PL spectra of the NWs with deposition time and provided an energy band diagram to give a plausible explanation of the origin of different emissions in the PL spectra. The PL spectra showed a broad strong UV-blue emission band and a weak red emission for 1 h deposited sample. We suggested that the UV and red emission from beta-Ga2O3 NWs are related to oxygen vacancies and impurities such as nitrogen, respectively. It was observed that the intensity of UV emission decreased with deposition time and this reduction was attributed primarily to the reduction of oxygen vacancies in the NWs.