Metal organic vapour-phase epitaxy growth of GaN wires on Si (111) for light-emitting diode applications

Abstract

GaN wires are grown on a Si (111) substrate by metal organic vapour-phase epitaxy on a thin deposited AlN blanket and through a thin SiNx layer formed spontaneously at the AlN/Si interface. N-doped wires are used as templates for the growth of core-shell InGaN/GaN multiple quantum wells coated by a p-doped shell. Standing single-wire heterostructures are connected using a metallic tip and a Si substrate backside contact, and the electroluminescence at room temperature and forward bias is demonstrated at 420 nm. This result points out the feasibility of lower cost nitride-based wires for light-emitting diode applications.

Figure 1

SEM picture of GaN wires. 45° tilted view of GaN wires grown by MOVPE on Si (111) with an intermediate AlN layer.

Figure 2

X-ray diffraction measurements of GaN wires grown on Si (111) with an intermediate AlN layer. (a) Symmetric Θ-2Θ scan performed on a laboratory setup (approximately 0.179 nm Co-wavelength) and indexed with Si, GaN and AlN Bragg K_α1 reflections. Dots and squares correspond respectively to the K_α2 and K_β excitation wavelengths. The broad and low intensity peak around 51° (see the triangle) is attributed to a diffraction tail of the Si substrate. (b) Rocking curves (Δω-scan) of the GaN (0002) and (0004) peaks. (c,d) Grazing incidence X-ray diffraction performed at ESRF along the $\left[22\stackrel{￣}{4}\right]$ silicon direction (approximately 0.1203 nm wavelength and 0.18° incidence).

Figure 3

HRTEM imaging of the GaN/AlN/Si interface (a,b). Observation along the $\left[10\stackrel{￣}{1}0\right]$ zone axis showing the materials stacking.

Figure 4

Electroluminescence measurements. Electroluminescence spectra of a single InGaN/GaN core-shell wire LED structure measured at 300 K with a metallic tip (> 20 V) for 2, 10, 25, 40 and 60 μA. The inset shows a schematic view of the contact.