Near infrared electroluminescence of ZnMgO/InN core–shell nanorod heterostructures grown on Si substrate

Abstract

This paper presents a systematic investigation of a ZnMgO/InN core-shell nanorods heterojunction device on a p-Si substrate. Here we demonstrated the heteroepitaxial growth of the well-aligned ZnMgO/InN core-shell nanorods structure, which enabled an increased heterojunction area to improve the carrier injection efficiency of nanodevices by plasma-assisted molecular beam epitaxy combined with metal-organic chemical vapor deposition. In situ X-ray photoelectron spectroscopy measurements were performed on the ZnMgO nanorods, the interface of ZnMgO/InN and the InN core-shell nanorods to fully understand the structure and working mechanism of the heterojunction device. The current transport mechanism has been discussed in terms of the characteristics of current-voltage and the energy band diagram of the n-InN/ZnMgO/p-Si heterojunction. At a low forward voltage, the current transport followed the dependence of I ∼ V(1.47), which was attributed to the deep-level assisted tunneling. When the forward voltage was larger than 10 V, the current followed the relation of I ∼ V(2) because of the radiative recombination process. In accordance with the above conclusion, the near-infrared electroluminescence of the diode could be observed after the forward bias voltage up to 11.6 V at room temperature. In addition, the size quantization effect and the intrinsic electron accumulation of the InN core-shell nanorods were investigated to explain the blueshift and broadened bandwidth. Furthermore, the light output power of about 0.6 microwatt at a fixed wavelength of 1500 nm indicated that our study will further provide a useful route for realizing the near-infrared electroluminescence of InN on Si substrate.

Development of in situ characterization techniques in molecular beam epitaxy

“…With XPS, Lin et al also investigated the chemical bonding at the Y 2 O 3 /GaSb interface grown by MBE and atomic layer deposition (ALD) [157] . Compared to surface property analysis, XPS is based on in-depth research, being able to serve as a reference for process optimization and study of the device operation mechanisms [158,159] . Maiti et al gained an understanding of the chemical composition of the grown molybdenum oxide (β-MoO 3 ) films by XPS, revealing a shift of the Mo 3d peaks towards lower binding energies, and a shift of the O 1s core level from lattice oxygen (O L ) peak to oxygen vacancies (O V ) peak, with increasing temperatures, indicating the reduction in Mo oxidation states [158] .…”

“…Compared to surface property analysis, XPS is based on in-depth research, being able to serve as a reference for process optimization and study of the device operation mechanisms [158,159] . Maiti et al gained an understanding of the chemical composition of the grown molybdenum oxide (β-MoO 3 ) films by XPS, revealing a shift of the Mo 3d peaks towards lower binding energies, and a shift of the O 1s core level from lattice oxygen (O L ) peak to oxygen vacancies (O V ) peak, with increasing temperatures, indicating the reduction in Mo oxidation states [158] . Ultraviolet photoemission spectroscopy (UPS) is mainly used to characterize the electronic band structure, Fermi energy level position, electronic density of states, and other information of materials, with high sensitivity and resolution for the analysis of surface electronic properties.…”