Determination of critical diameters for intrinsic carrier diffusion-length of GaN nanorods with cryo-scanning near-field optical microscopy

Y T Chen,K F Karlsson,J Birch,P O Holtz

doi:10.1038/srep21482

Abstract

Direct measurements of carrier diffusion in GaN nanorods with a designed InGaN/GaN layer-in-a-wire structure by scanning near-field optical microscopy (SNOM) were performed at liquid-helium temperatures of 10 K. Without an applied voltage, intrinsic diffusion lengths of photo-excited carriers were measured as the diameters of the nanorods differ from 50 to 800 nm. The critical diameter of nanorods for carrier diffusion is concluded as 170 nm with a statistical approach. Photoluminescence spectra were acquired for different positions of the SNOM tip on the nanorod, corresponding to the origins of the well-defined luminescence peaks, each being related to recombination-centers. The phenomenon originated from surface oxide by direct comparison of two nanorods with similar diameters in a single map has been observed and investigated.

Highlights

SNOM related studies have been performed in the infrared regime and at room temperature
Measurements of carrier diffusion in single InGaN/GaN layer-in-a-wire structures with SNOM were performed at low temperatures (10 K)
An illustration of the experimental setup for SNOM is shown in the inset of Fig. 1(a)

Summary

Introduction

SNOM related studies have been performed in the infrared regime and at room temperature. Measurements of carrier diffusion in single InGaN/GaN layer-in-a-wire structures with SNOM were performed at low temperatures (10 K).

Results

Conclusion