Mesoporous GaN Made by Selective Area Sublimation for Efficient Light Emission on Si Substrate

Abstract

Selective area sublimation of thin (≤0.3 μm) GaN-on-Si epitaxial layers through nanoholes of an incomplete monolayer of SixNy results in the formation of mesoporous GaN. This morphologic change from a two-dimensional flat layer to a nanostructured material presents the unexpected property of a huge increase (more than three orders of magnitude) of the GaN band edge photoluminescence intensity. Furthermore, the integrated photoluminescence intensity of such mesoporous GaN layers is comparable to a high quality 3.5 μm-thick GaN-on-sapphire epitaxial layer or a 350 μm-thick GaN substrate. Different possible mechanisms are discussed to explain the origin of the strong improvement of the optical properties.