X-Ray Photoelectron Spectroscopy and Raman Scattering Studies of ALD Alumina Coated ZnTe Nanowires

Semiconductor nanowires (NWs) represent a versatile platform for evaluating novel phenomena at the nanoscale and also exhibit high potential for applications in future electronic, photovoltaic, and optoelectronic devices [1]. Moreover, the fabrication of core-shell heterostructures based on semiconductor NW-insulator heterostructures further enable the generation of devices with diverse functions. In this work, the fabrication of core-shell heterostructures, via metal-catalyzed vapor–liquid–solid synthesis of Zinc Telluride (ZnTe) NWs followed by the conformal coating of alumina (Al₂O₃) by atomic layer deposition (ALD), has been demonstrated.  While the former is a direct band gap (~ 2.26 eV), II-VI semiconductor in the blue-green region of the spectrum, the latter is a high band gap (~ 6.4 eV) insulator that is amorphous. Here, preliminary x-ray photo electron spectroscopy (XPS) and Raman scattering results on the ZnTe/Al₂O₃ core-shell nanostructures are presented and discussed. Additionally, photoluminescence spectra of coated and uncoated ZnTe NWs are discussed in light of the variations in peak position and line-width.

Reference:

1. J. Wallentin, et al, InP nanowire array solar cells achieving 13.8 % efficiency by exceeding the ray optics limit, Science 339, pp. 1057-1060, (2013).