Transport imaging for contact-free measurements of minority carrier diffusion in GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires

Abstract

Minority carrier diffusion lengths (Ld) are measured for GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires using a technique based on imaging of recombination luminescence. The effect of shell material on transport properties is measured. An AlGaN shell produces Ld values in excess of 1 μm and a relative insensitivity to wire diameter. An InGaN shell reduces effective diffusion length, while a dependence of Ld on diameter is observed for uncoated nanowires.

Optical attenuation coefficient in individual ZnO nanowires

“…This is achieved by placing the SEM in "spot mode" operation at a fixed point on the sample and then scanning the NSOM probe. The resulting information can provide detailed information on waveguiding, as presented here, or can be used to optically determine, in a non-contact manner, the diffusion length of minority carriers [12,13]. Figure 2 shows a schematic of the experiment.…”

Imaging transport in nanowires using near-field detection of light

“…Spatially resolved imaging of resulting luminescence allows observation of the motion of that charge, acquiring steady-state images of the light emitted as some fraction of carriers recombine along their path of travel. While some related experiments have utilized a laser source for generation of charge [1][2][3], we have more recently utilized this approach at very high spatial resolution for the study of transport in nanostructures by integrating near-field optical microscopy, which provides spatial resolution beyond the far-field diffraction limit, with the high resolution and spatial control of an electron beam in an SEM for generation of charge [4,5].…”

Spontaneous Formation of AlInN Core–Shell Nanorod Arrays by Ultrahigh-Vacuum Magnetron Sputter Epitaxy

“…[10][11][12][13] However, the synthesis of ternary AlInN core-shell nanorods is still limited. The AlInN alloy, direct-bandgap semiconductor, was understood to exhibit key properties due to the broadest bandgap range, 0.7-6.2 eV, among the direct bandgap III-nitride semiconductors.…”

“…The group III-nitride, including AlN, GaN, InN, and their alloys, nanomaterials have generated great interest in the past decade because high-performance semiconductor nanodevices are expected to be developed, such as high-sensitivity sensors, highresponsivity photodetectors, and high-brightness light-emitting devices. [1][2][3][4][5][6][7][8][9][10][11][12][13] To enhance the nanodevices' performance, single or multiple heterojunctions grown along the length of a nanorod or in its radial direction (core-shell structure) can be used. [8][9][10][11][12][13] In particular, for making the bottom electrodes on many nonconducting substrates and simplify device fabrication processes.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] To enhance the nanodevices' performance, single or multiple heterojunctions grown along the length of a nanorod or in its radial direction (core-shell structure) can be used. [8][9][10][11][12][13] In particular, for making the bottom electrodes on many nonconducting substrates and simplify device fabrication processes. Moreover, a high growth rate of the nanorods implies that a full structure of on-chip nanodevices may be fabricated within a few hours in the same chamber without breaking vacuum, which is an attractive scheme for large-scale production.…”