Temperature Characterization of Unipolar-Doped Electroluminescence in Vertical GaN/AlN Heterostructures

Weidong Zhang,Elliott R Brown,David J Meyer,Paul R Berger,Tyler A Growden,David F Storm

doi:10.3390/en14206654

Abstract

An electroluminescence (EL) phenomenon in unipolar-doped GaN/AlN/GaN double-barrier heterostructures—without any p-type contacts—was investigated from 4.2 K to 300 K. In the range of 200–300 K, the extracted peak photon energies agree with the Monemar formula. In the range of 30 to 200 K, the photon energies are consistent with A-exciton emission. At 4.2 K, the exciton type likely transforms into B-exciton. These studies confirm that the EL emission comes from a cross-bandgap (or band-to-band) electron-hole radiative recombination and is excitonic. The excitons are formed by the holes generated through interband tunneling and the electrons injected into the GaN emitter region of the GaN/AlN heterostructure devices.

Highlights

In GaN-based LEDs and laser diodes, two types of contacts are required for generating light emission
We hypothesized that the holes necessary for the EL are generated near the depleted spacer region on the collector side of GaN/AlN resonant tunneling diodes (RTDs) via Zener interband tunneling, which is enabled by the unusually high electric fields—on the order of ∼5 × 106 V/cm—originating from the polarization effect that is native to Wurtzite heterostructures (Figure 1d) [2]
Negative differential resistance (NDR) with a chair-like self-oscillation-related pattern is displayed in the range of 7.0–7.5 V, which confirms the high quality of the plasma-assisted molecular-beam epitaxy (PAMBE)-grown GaN/AlN heterostructure

Summary

Introduction

In GaN-based LEDs and laser diodes, two types of contacts are required for generating light emission. One is n-type, which acts as reservoir for electrons; the other is p-type, which acts as reservoir for holes. GaN/AlN/GaN double-barrier resonant tunneling diodes (RTDs) without any p-type contacts (Figure 1a–c) [1]. We hypothesized that the holes necessary for the EL are generated near the depleted spacer region on the collector side of GaN/AlN RTDs via Zener interband tunneling, which is enabled by the unusually high electric fields—on the order of ∼5 × 106 V/cm—originating from the polarization effect that is native to Wurtzite heterostructures (Figure 1d) [2]. The holes migrate to the emitter region, where they can radiatively recombine with those electrons injected from the emitter contact (Figure 1d)

Methods

Results

Conclusion