Repeatable Room Temperature Negative Differential Conductance in GaN/AlN Resonant Tunneling Diodes

TL;DR

This study demonstrates the fabrication and analysis of GaN/AlN resonant tunneling diodes that exhibit repeatable negative differential conductance at room temperature, supported by experimental results and an electrostatic model.

Contribution

It introduces a novel GaN/AlN heterostructure design with a developed electrostatic model explaining its resonant tunneling behavior at room temperature.

Findings

Room temperature negative differential conductance observed

Peak current density of ~6.4 kA/cm^2 achieved

Model accurately predicts resonant and threshold voltages

Abstract

Double barrier GaN/AlN resonant tunneling heterostructures have been grown by molecular beam epitaxy on the (0001) plane of commercially available bulk GaN substrates. Resonant tunneling diodes were fabricated; room temperature current-voltage measurements reveal the presence of a negative differential conductance region under forward bias with peak current densities of ~6.4 $kA/cm^2$ and a peak to valley current ratio of ~1.3. Reverse bias operation presents a characteristic turn-on threshold voltage intimately linked to the polarization fields present in the heterostructure. An analytic electrostatic model is developed to capture the unique features of polar-heterostructure-based resonant tunneling diodes; both the resonant and threshold voltages are derived as a function of the design parameters and polarization fields. Subsequent measurements confirm the repeatability of the negative conductance and demonstrate that III-nitride tunneling heterostructures are capable of robust resonant transport at room temperature.