Quantum transport in GaN/AlN double-barrier heterostructure nanowires

TL;DR

This study explores quantum transport phenomena in GaN/AlN nanowires with double barriers, revealing Coulomb blockade effects and resonant tunneling behaviors at low temperatures, with potential implications for nanoscale electronic devices.

Contribution

It demonstrates controlled quantum confinement and tunneling in GaN/AlN nanowires with abrupt interfaces, advancing understanding of their electronic transport properties.

Findings

Coulomb blockade dominates at low temperatures in nanowires.

Resonant tunneling observed with negative differential resistance up to 150 K.

Quantum dot behavior depends on well and barrier thicknesses.

Abstract

We investigate electronic transport in n-i-n GaN nanowires with and without AlN double barriers. The nanowires are grown by catalyst-free, plasma-assisted molecular beam epitaxy enabling abrupt GaN/AlN interfaces as well as longitudinal n-type doping modulation. At low temperature, transport in n-i-n GaN nanowires is dominated by the Coulomb blockade effect. Carriers are confined in the undoped middle region, forming single or multiple islands with a characteristic length of ~100 nm. The incorporation of two AlN tunnel barriers causes confinement to occur within the GaN well in between. In the case of 6-nm-thick wells and 2-nm-thick barriers, we observe characteristic signatures of Coulomb-blockaded transport in single quantum dots with discrete energy states. For narrower wells and barriers, Coulomb-blockade effects do not play a significant role while the onset of resonant tunneling via the confined quantum levels is accompanied by a negative differential resistance surviving up to ~150 K.