Epitaxial Growth of GaN Core and InGaN/GaN Multiple Quantum Well Core/Shell Nanowires on a Thermally Conductive Beryllium Oxide Substrate

Abstract

Beryllium oxide (BeO) belongs to a very unique material family that exhibits the divergent properties of high thermal conductivity and high electrical resistivity. BeO has the same crystal structure as GaN, and the absolute difference in the lattice constants is less than 17%. Here, the growth of GaN nanowires (NWs) on the polycrystalline BeO substrate is reported for the first time. The NWs are grown by a vapor–liquid–solid approach using a showerhead-based metal–organic chemical vapor deposition. The growth direction of NWs is along the m -axis on all planes of the substrate, and it is confirmed by transmission electron microscopy (TEM) and selected area electron diffraction (SAED) patterns. The vertical and tilted growth of NWs is due to the different planes of the substrate such as the m -plane, a -plane, and semipolar planes and is confirmed by X-ray diffraction. Subsequently, the GaN shell and InGaN/GaN multiple quantum wells (MQWs) are coaxially grown using a vapor–solid approach in the same reactor. A very high crystal quality is verified by TEM and SAED and is also confirmed by measuring the photoluminescence. The optical emission is tuned for the entire visible spectrum by increasing the indium incorporation in InGaN quantum wells. The conformal growth of InGaN/GaN MQW shells and the defect-free nature of the structure are confirmed from spatially resolved cathodoluminescence. This study will provide a platform for researchers to grow GaN NWs on the BeO substrate for a range of optical and electrical applications.

Epitaxial growth of 1D GaN-based heterostructures on various substrates for photonic and energy applications

“…The crystal structure of BeO is identical to that of GaN, and the absolute difference in lattice constants is less than 17%. For the first time, the formation of GaN NWs on a polycrystalline BeO substrate was reported by Johar et al 81 The optimal strategy for growing single-crystalline GaN atop polycrystalline BeO is to generate single-crystalline GaN NWs with the same crystal orientation. The GaN NWs were synthesized on the BeO substrate using the VLS approach employing Au as a catalyst.…”

Stable and Efficient Photoelectrochemical Water Splitting of GaN Nanowire Photoanode Coated with Au Nanoparticles by Hot-Electron-Assisted Transport

“…In recent years, one-dimensional (1D) nanostructures have been extensively studied for PEC water splitting. In 1D nanostructures, lattice-mismatch constraints are reduced, which minimizes the dislocation density and piezoelectric polarization fields. − In addition, 1D nanostructures increase the reactive surface area, promote charge separation, and minimize optical losses. To further improve the optical, electronic, and catalytic properties, semiconductors are decorated with noble metal nanoparticles (NPs). − These noble metal NPs enhance the utilization of light by photoelectrodes through light scattering, light concentration, plasmon-induced resonance energy transfer, and hot electron injection.…”