On the impact of indium distribution on the electronic properties in InGaN nanodisks

Abstract

We analyze an epitaxially grown heterostructure composed of InGaN nanodisks inserted in GaN nanowires in order to relate indium concentration to the electronic properties. This study was achieved with spatially resolved low-loss electron energy-loss spectroscopy using monochromated electrons to probe optical excitations—plasmons—at nanometer scale. Our findings show that each nanowire has its own indium fluctuation and therefore its own average composition. Due to this indium distribution, a scatter is obtained in plasmon energies, and therefore in the optical dielectric function, of the nanowire ensemble. We suppose that these inhomogeneous electronic properties significantly alter band-to-band transitions and consequently induce emission broadening. In addition, the observation of tailing indium composition into the GaN barrier suggests a graded well-barrier interface leading to further inhomogeneous broadening of the electro-optical properties. An improvement in the indium incorporation during growth is therefore needed to narrow the emission linewidth of the presently studied heterostructures.

Surface Passivation of GaN Nanowires for Enhanced Photoelectrochemical Water-Splitting

“…Catalyst-free, vertically aligned GaN NWs were grown on an n-Si (111) substrate using PA-MBE (Veeco GEN930). − The native oxide on the Si substrate was removed by immersing it in 10% hydrofluoric acid (HF) for 30 s before loading it into the MBE chamber. The growth parameters included a temperature of ∼750 °C, a nitrogen flow rate of 1.0 sccm, a forward plasma power of ∼350 W, and a Ga beam equivalent pressure of ∼6 × 10 –8 Torr.…”

Photoinduced entropy of InGaN/GaN p-i-n double-heterostructure nanowires

“…4(a) suggests the presence of localized states induced by potential fluctuations in indium-rich clusters within the active InGaN layers. [46][47][48] These states are introduced by the enhanced formation of In-N chains in the immediate vicinity of the threading dislocations, hence limiting non-radiative recombination of carriers at the dislocation cores. 49,50 As observed in Fig.…”