7 μm (length) channel area. In this way, the current-voltage (I-V) curve of the representative β-Ga2O3 NW array is measured and shown in Figure 5b, where the resistance is estimated to be approximately 2 × 1012 Ω as
the current is approximately 5 pA under 10-V bias. As a result, the resistance is approximately 4 × 1014 Ω per individual NW (approximately 2 × 1012 × 200 Ω, as 200 NWs are connected in parallel). Then, the resistivity can be estimated as 2 × 1012 × 200 Ω × 3.7 μm/3.14/502 nm2 = 8.5 × 107 Ω cm, considering the NW diameter of approximately 100 nm. Notably, other metal electrodes with different work functions Selleck BLZ945 such as Al (approximately 4.2 eV) and Au (approximately 5.3 eV) are also prepared, in which the results attained are all similar as shown in Figure 5b, suggesting the highly insulating property of the NWs here. This resistivity is relatively larger than those of doped and undoped β-Ga2O3 NWs reported in the literature PARP inhibitor [4, 6, 13], which can be
attributed to the moderate growth temperature employed in this work such that less impurity would be incorporated, showing its prospective in dielectric materials for advanced III-V nanowire-based nanoelectronics. Figure 5 Electrical properties of the β-Ga 2 O 3 NWs grown at the Ar:O 2 flow ratio of 100:2. (a) SEM image of the printed β-Ga2O3 NW arrays patterned with Ni electrodes on both ends. (b) The corresponding I-V curve of the β-Ga2O3 NW arrays with Ni, Al, and Au as electrodes. Conclusions Highly crystalline β-Ga2O3 NWs are synthesized by a solid-source chemical vapor deposition method employing GaAs powders as the source material and mixture aminophylline of Ar and O2 as the carrier gas. The NWs grown at the Ar:O2 flow ratio of 100:2 are long (>10 μm) with a uniform
diameter of approximately 100 nm and smooth surfaces. X-ray diffraction and selected area electron diffraction results confirm the monoclinic structure of the obtained NWs with varied growth orientations along the low-index planes. Furthermore, the reflectance spectrum demonstrates the bandgap of β-Ga2O3 NWs being 4.94 eV, while the electrical measurement deduces the corresponding resistivity of 8.5 × 107 Ω cm. All these results indicate the successful synthesis of a large-bandgap Ga2O3 material in III-V-compatible growth conditions, illustrating the promising potential for dielectric materials used for III-V nanowire-based metal-oxide-semiconductor technology. Acknowledgements This research was financially supported by the Early Career Scheme of the Research Grants Council of Hong Kong SAR, China (Grant Number CityU139413), the GSI-IX supplier National Natural Science Foundation of China (Grant Number 51202205), the Guangdong National Science Foundation (Grant Number S2012010010725), and the Science Technology and Innovation Committee of Shenzhen Municipality (Grant Number JCYJ20120618140624228) and was supported by a grant from the Shenzhen Research Institute, City University of Hong Kong. References 1.