Nearly Lattice-Matched GaN Distributed Bragg Reflectors with Enhanced Performance

Abstract

Heavy silicon-doping in GaN generally causes a rough surface and saturated conductivity, while heavily silicon-doped n++-AlGaN with ≤5% aluminum can maintain an atomically flat surface and exhibit enhanced conductivity. Given this major advantage, we propose using multiple pairs of heavily silicon-doped n++-Al0.01Ga0.99N and undoped GaN instead of widely used multiple pairs of heavily silicon-doped n++-GaN and undoped GaN for the fabrication of a lattice-matched distributed Bragg reflector (DBR) by using an electrochemical (EC) etching technique, where the lattice mismatch between Al0.01Ga0.99N and GaN can be safely ignored. By means of using the EC etching technique, the n++-layers can be converted into nanoporous (NP) layers whilst the undoped GaN remains intact, leading to a significantly high contrast in refractive index between NP-layer and undoped GaN and thus forming a DBR. Our work demonstrates that the NP-Al0.01Ga0.99N/undoped GaN-based DBR exhibits a much smoother surface, enhanced reflectivity and a wider stopband than the NP-GaN/undoped GaN-based DBR. Furthermore, the NP-Al0.01Ga0.99N/undoped GaN-based DBR sample with a large size (up to 1 mm in width) can be obtained, while a standard NP-GaN/undoped GaN-based DBR sample obtained is typically on a scale of a few 100 μm in width. Finally, a series of DBR structures with high performance, ranging from blue to dark yellow, was demonstrated by using multiple pairs of n++-Al0.01Ga0.99N and undoped GaN.

Antireflective GaN Nanoridge Texturing by Metal-Assisted Chemical Etching via a Thermally Dewetted Pt Catalyst Network for Highly Responsive Ultraviolet Photodiodes

“…Therefore, anisotropic wet chemical etching is employed to produce GaN AR structures. Doped GaN , are typically utilized due to a low etching efficiency of undoped GaN, , forming porous structures. However, previous literature shows that Schottky barrier diodes based on doped GaN exhibit higher leakage current and lower UV responsivity compared to those made on undoped GaN thin films due to a lower concentration of Ga vacancies in undoped GaN epi-layers. , In addition, undoped GaN exhibits higher electron mobility than the doped one, which exhibits better application potential in high-speed devices.…”

All-BN distributed Bragg reflectors fabricated in a single MOCVD process

“…Another approach to obtain the needed reflective index contrast is to use porous structures. However, such structures require a selective post-fabrication etching process [30][31][32][33][34][35].…”

Enhancement of InGaN Quantum Well Photoluminescence in a Tamm Metal/Porous-DBR micro-Cavity

“…In this work, we propose a novel way to form a lasing micro-cavity (MC) for a GaN based VCSEL device, by combining recent progress in the fabrication of highly 2 > PJ-014066-2023 < reflective porous-GaN/GaN DBR structures [6], [7], [8], [9], [10], [11] and a so-called Tamm plasmons [12], [13] in which photonic surface state is formed in the cavity between a DBR mirror and a thin metal film [11], [14], [15], [16], [17], [18]. Such porous-DBRs have an advantage of a very high refractive index contrast between GaN and porous-GaN layers in a stack, due to air filling the pores and are nearly stress free due to lack of lattice constant mismatch.…”