Nanostructure analysis of InGaN/GaN quantum wells based on semi-polar-faced GaN nanorods

Abstract

We demonstrate a series of InGaN/GaN double quantum well nanostructure elements. We grow a layer of 2 μm undoped GaN template on top of a (0001)-direction sapphire substrate. A 100 nm SiO 2 thin film is deposited on top as a masking pattern layer. This layer is then covered with a 300 nm aluminum layer as the anodic aluminum oxide (AAO) hole pattern layer. After oxalic acid etching, we transfer the hole pattern from the AAO layer to the SiO 2 layer by reactive ion etching. Lastly, we utilize metal-organic chemical vapor deposition to grow GaN nanorods approximately 1.5 μm in size. We then grow two layers of InGaN/GaN double quantum wells on the semi-polar face of the GaN nanorod substrate under different temperatures. We then study the characteristics of the InGaN/GaN quantum wells formed on the semi-polar faces of GaN nanorods. We report the following findings from our study: first, using SiO 2 with repeating hole pattern, we are able to grow high-quality GaN nanorods with diameters of approximately 80-120 nm; second, photoluminescence (PL) measurements enable us to identify Fabry-Perot effect from InGaN/GaN quantum wells on the semi-polar face. We calculate the quantum wells' cavity thickness with obtained PL measurements. Lastly, high resolution TEM images allow us to study the lattice structure characteristics of InGaN/GaN quantum wells on GaN nanorod and identify the existence of threading dislocations in the lattice structure that affects the GaN nanorod's growth mechanism.

Thickness Dependence on Interfacial and Electrical Properties in Atomic Layer Deposited AlN on c-plane GaN

“…Realizing high-performance GaN-based devices requires metal/GaN interface with a minimum interface state density, which can act as electron traps or limit to modulate the barrier heights according to metal work function by pinning the Fermi level [ 5 , 6 ]. For other GaN-based device improvement techniques, some methods such as coalescence overgrowth of GaN nanocolumns, nonpolar m -plane GaN, nanoimprint GaN template, and semi-polar face GaN nanorods have also been demonstrated [ 7 – 11 ]. Among III-nitride compound semiconductors, aluminum nitride (AlN) can be applied to UV detectors, short-wavelength emitters and detectors, due to its high bandgap (∼ 6.2 eV), high thermal conductivity, high electric resistance, as well as low expansion at high temperatures [ 12 , 13 ].…”

Efficient Carrier Injection, Transport, Relaxation, and Recombination Associated with a Stronger Carrier Localization and a Low Polarization Effect of Nonpolar m-plane InGaN/GaN Light-Emitting Diodes

“…Auger recombination [ 14 , 15 ] and carrier delocalization from indium-rich regions to dislocations [ 16 ] have also been proposed. The growth of III-nitrides along the nonpolar m - and a -axes [ 11 , 17 , 18 ], semipolar axis [ 19 ], and - c -axis ( nitrogen -polar) [ 20 ] can overcome polarization effects. Without polarization effects in a nonpolar m -plane LED ( m -LED), more uniform hole distribution among the wells and suppressed electron overflow out of the electron blocking layer can significantly reduce the electron leakage current and efficiency droop [ 11 ].…”