Abstract
Distributed Bragg reflectors (DBRs) are essential components for the development of optoelectronic devices. For many device applications, it is highly desirable to achieve not only high reflectivity and low absorption, but also good conductivity to allow effective electrical injection of charges. Here, we demonstrate the wafer-scale fabrication of highly reflective and conductive non-polar gallium nitride (GaN) DBRs, consisting of perfectly lattice-matched non-polar (11–20) GaN and mesoporous GaN layers that are obtained by a facile one-step electrochemical etching method without any extra processing steps. The GaN/mesoporous GaN DBRs exhibit high peak reflectivities (>96%) across the entire visible spectrum and wide spectral stop-band widths (full-width at half-maximum >80 nm), while preserving the material quality and showing good electrical conductivity. Such mesoporous GaN DBRs thus provide a promising and scalable platform for high performance GaN-based optoelectronic, photonic, and quantum photonic devices.
Highlights
III-nitride materials have achieved commercial success in the realization of highly efficient photonic devices including light emitting diodes (LEDs)[4] and lasers[5], and exhibit particular advantages for the development of quantum light sources[6], and the exploration of quantum information science[7,8,9] and light-matter interactions[2,10]
Perhaps more fundamentally in the context of blue or green emitters, InGaN active layers with intermediate and high indium content are known to be very sensitive to thermal damage[27] which may limit the application of this approach. (This issue has yet to be thoroughly evaluated)
The development of mesoporous (MP) Distributed Bragg reflectors (DBRs), has attracted increasing attention in recent years since tuning of the spectral response may be achieved by varying the porosity, the layer thicknesses, and the number of repeat periods[28,29,30,31]
Summary
Tongtong Zhu[1], Yingjun Liu[1], Tao Ding[2], Wai Yuen Fu3, John Jarman[1], Christopher Xiang Ren[1], R. The local refractive index of the NID-GaN layers might be altered by the vertical etching, we stress the fact that the measured reflectivity values are very close to the theoretical values and the density of such vertical etching pathways is considered to be low enough (~2 × 109 cm−2), that the global reflectivity at the wafer scale (~cm) is only marginally affected and that the majority of the material should exhibit a sufficient reflectivity, unaffected by these issues, to allow the fabrication of devices such as LEDs and micropillar cavity structures for single photon sources with reasonable yield. These measurements show that the non-polar GaN/MP-GaN DBR is electrically conductive, which will be compatible with electrically driven GaN optoelectronic devices
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