GaN Nanowall Network: A new possible route to obtain efficient p-GaN and enhanced light extraction

TL;DR

This paper demonstrates that GaN nanowall networks can significantly improve light extraction and Mg doping efficiency in p-GaN, offering a promising new approach for optoelectronic device enhancement.

Contribution

It introduces a novel GaN nanowall network growth method that enhances light emission and Mg incorporation for efficient p-GaN, overcoming previous limitations.

Findings

Photoluminescence enhancement of approximately 3.2 times in doped GaN

Observation of two broad blue luminescence peaks at 2.95 and 2.7 eV in heavily doped GaN

High Mg incorporation (~10^20 atoms/cm^3) with maintained band edge emission

Abstract

We demonstrate that GaN formed in a Nanowall Network (NwN) morphology can overcome fundamental limitations in optoelectronic devices, and enable high light extraction and effective Mg incorporation for efficient p-GaN. We report the growth of Mg doped GaN Nanowall network (NwN) by plasma assisted molecular beam epitaxy (PA-MBE) that is characterized by Photoluminescence (PL) spectroscopy, Raman spectroscopy, high-resolution X-ray diffraction (HR-XRD), X-ray photoelectron spectroscopy (XPS) and Secondary ion mass spectroscopy (SIMS). We record a photo-luminescence enhancement ($ \approx $3.2 times) in lightly doped GaN as compared to that of undoped NwN. Two distinct (and broad) blue luminescence peaks appears at 2.95 and 2.7 eV for the heavily doped GaN (Mg $>10^{20}$ atoms $cm^{-3}$), of which the 2.95 eV peak is sensitive to annealing is observed. XPS and SIMS measurements estimate the incorporated Mg concentration to be $10^{20}$ atoms $cm^{-3}$ in GaN NwN morphology, while retaining its band edge emission at $\approx$ 3.4 eV. A higher Mg accumulation towards the GaN/Al$_2$O$_3$ interface as compared to the surface was observed from SIMS measurements.