ZrN nucleation layer provides backside ohmic contact to MBE-grown GaN nanowires

TL;DR

This paper demonstrates that ZrN nucleation layers enable backside ohmic contact to GaN nanowires grown by MBE, facilitating electrically conductive and optically transparent contacts for nanowire-based light-emitting devices.

Contribution

It introduces ZrN as an effective nucleation layer that provides ohmic contact to GaN nanowires, a novel approach for improving nanowire device integration.

Findings

ZrN provides ohmic contact to n-type GaN nanowires.

Single nanowire measurements show highly rectifying p-n junctions.

Feasibility of ZrN-based backside contact for nanowire devices is confirmed.

Abstract

Self-assembled GaN nanowires are typically grown on Si substrates with convenient nucleation layers. Light-emitting devices based on arrays of GaN nanowires require that the nucleation layer is electrically conductive and optically nontransparent to prevent the absorption of generated light in the Si substrate. This study reports the molecular beam epitaxial growth of GaN nanowires on ZrN nucleation layers sputtered on sapphire and demonstrates that ZrN provides ohmic contact to dense vertical arrays of n-type GaN nanowires. The ohmic nature of the ZrN/n-type GaN nanowire contact is evidenced by the measurement of the current-voltage characteristics of individual as-grown nanowires using nanomanipulators in a scanning electron microscope. The limitations and advantages of single-nanowire measurements are discussed, and approaches to overcome these limitations are proposed. The feasibility of this concept is demonstrated by the measurement of single NWs with a p-n junction, exhibiting highly rectifying characteristics.