Repeatable Room Temperature Negative Differential Resistance in AlN/GaN Resonant Tunneling Diodes Grown on Sapphire

Abstract

AbstractResonant tunneling diodes (RTDs) are candidates for high power terahertz oscillators, and form the basis for understanding the quantum confinement and vertical transport in quantum structures such as quantum cascade lasers and quantum cascade detectors. In this work, repeatable negative differential resistance (NDR) is achieved in AlN/GaN RTDs grown on sapphire substrate by plasma‐assisted molecular‐beam epitaxy. Two reproducible NDR regions sequentially following two preresonance replicas are demonstrated at room temperature. A current region exhibiting negative correlation with temperature and oscillation‐like features is first identified under reverse bias, which is interpreted as a combined contribution of weak resonant tunneling channels through different bound states in the well. The revealed peak‐to‐valley current ratio ranges from 1.1 to 1.8, and peak current density ranges from 5 to 164 kA cm−2. Using an analytic model, resonant tunneling transports in both bias directions are quantitatively characterized and show good agreements with experiment results, demonstrating the capability of accurate quantum transport control using III‐nitride grown on sapphire substrate. The findings will promote the implementation of low cost III‐nitride monolithic microwave circuits and resonant tunneling structures based on sapphire, SiC, and even silicon substrates.