Fabrication of Current Confinement Aperture Structure by Transforming a Conductive GaN:Si Epitaxial Layer into an Insulating GaOx Layer

Abstract

We report here a simple and robust process to convert embedded conductive GaN epilayers into insulating GaOx and demonstrate its efficacy in vertical current blocking and lateral current steering in a working LED device. The fabrication processes consist of laser scribing, electrochemical (EC) wet-etching, photoelectrochemical (PEC) oxidation, and thermal oxidization of a sacrificial n(+)-GaN:Si layer. The conversion of GaN is made possible through an intermediate stage of porosification where the standard n-type GaN epilayers can be laterally and selectively anodized into a nanoporous (NP) texture while keeping the rest of the layers intact. The fibrous texture of NP GaN with an average wall thickness of less than 100 nm dramatically increases the surface-to-volume ratio and facilitates a rapid oxidation process of GaN into GaOX. The GaOX aperture was formed on the n-side of the LED between the active region and the n-type GaN layer. The wavelength blueshift phenomena of electroluminescence spectra is observed in the treated aperture-emission LED structure (441.5 nm) when compared to nontreated LED structure (443.7 nm) at 0.1 mA. The observation of aperture-confined electroluminescence from an InGaN LED structure suggests that the NP GaN based oxidation will play an enabling role in the design and fabrication of III-nitride photonic devices.

Mesoporous GaN for Photonic Engineering—Highly Reflective GaN Mirrors as an Example

“…Novel configurations and shapes of GaN can be obtained through curvature-driven mass transport at elevated temperatures . NP-GaN can also be used in directing and blocking current flow after its conversion to resistive GaOx . In this paper, we focus on the new possibility of using finely structured mesoporous GaN to control the index of refraction ( n ) of GaN, which is of crucial importance for optical engineering of GaN devices.…”