Characterization of GaN Nanowall Network and Optical Property of InGaN/GaN Quantum Wells by Molecular Beam Epitaxy

Abstract

A GaN nanowall network and InGaN/GaN quantum wells were grown on AlN/Si(111) substrates by molecular beam epitaxy (MBE). The morphology, polarity, structural, and optical properties of the GaN nanowall network were investigated. The lattice constants a 0= 3.193 Å and c 0 = 5.182 Å of the GaN nanowall network were obtained by X-ray diffraction (XRD), indicating that the GaN nanowall network is under low stress. Chemical etching test shows that the GaN nanowall network grown on an Al-polar buffer layer is Ga-polar. Photoluminescence (PL) spectra of InGaN/GaN quantum wells both on a GaN nanowall network and a GaN film were also measured. Different from the InGaN/GaN quantum wells on GaN film, the Fabry–Perot effect is not observed in the PL spectrum of the InGaN/GaN quantum wells on the GaN nanowall network owing to its antireflective porous structure. The emission wavelength gradually blue shifts from 408 to 391 nm with the decrease of temperature from 293 to 10 K. The GaN nanowall network grown on a Si substrate is not only compatible with mature Si micromachining technology but also may provide a novel nano-optical device.

Structural, optical and electronic properties of homoepitaxial GaN nanowalls grown on GaN template by laser molecular beam epitaxy

“…[18][19][20][21][22] The N to Ga ratio also determines the width of the nanowalls as reported previously.…”

“…Recently, a few research groups have reported the growth of GaN nanowall networks on sapphire 18,21 and Si(111) 19,20 using plasma assisted molecular beam epitaxy (PA-MBE). Most of the GaN nanowall networks have been grown heteroepitaxially on these substrates under extremely high N to Ga ux ratio conditions.…”

“…The LMBE growth of GaN layers was monitored by in situ RHEED and the typical RHEED pattern obtained for the GaN template and the LMBE grown GaN sample along [11][12][13][14][15][16][17][18][19][20] and directions have been presented in Fig. 1(a and b).…”

“…GaN nanowalls were grown on sapphire (lattice mismatch $14%) and Si(111) (lattice mismatch $16%) substrates using MBE technique in extremely N-rich condition and the growth process has been explained on the basis of large lattice mismatch, the mist dislocation and strain. [18][19][20][21][22] For GaN nanowalls grown on SiC substrate (lattice mismatch $3.5%) using ion beam assisted MBE, the growth process was explained on the basis of N-rich growth conditions in combination with high growth temperature and the energetic N ion irradiation during the growth. 15 For homoepitaxial growth of GaN nanowalls on GaN template, the effect of strain will be minimal.…”

Edge enhanced growth induced shape transition in the formation of GaN nanowall network

“…Most of the growth of porous GaN is achieved by top down approaches such as chemical etching 19 or ion bombardment 20 , which limit the device performance due to contamination, undesired interface and defect states, and degradation in crystallinity and composition. Previously, we have shown that by controlling V/III ratio, spontaneous formation of porous nanostructures can be achieved by using PA-MBE system, 21-24 which was followed by a few groups [25][26][27][28] . Investigations of the growth process of NwN are highly important to control shape and size of the pores, to enhance light extraction efficiency 22 .…”