In situ etching for total control over axial and radial nanowire growth

Abstract

We report a method using in situ etching to decouple the axial from the radial nanowire growth pathway, independent of other growth parameters. Thereby a wide range of growth parameters can be explored to improve the nanowire properties without concern of tapering or excess structural defects formed during radial growth. We demonstrate the method using etching by HCl during InP nanowire growth. The improved crystal quality of etched nanowires is indicated by strongly enhanced photoluminescence as compared to reference nanowires obtained without etching.

Position-controlled [100] InP nanowire arrays

“…In situ HCl etching is used to prevent lateral growth and to realize diameter uniformity along the NW axial direction. 23 Finally, we demonstrate control of position, diameter, length, yield, and tapering of defect-free pure zincblende [100] NW grown on InP (001) substrates.…”

“…The peaks from 1.36-1.40 eV are assigned to impurity-related emission. Note that no strong emission around 1.38 eV is observed, typical for a conduction band-to-acceptor transition due to carbon impurity, even 23 HCl is simultaneously switched on and off with TMI. Fig.…”

Single GaInP nanowire p-i-n junctions near the direct to indirect bandgap crossover point

“…13 Hydrogen chloride (HCl) was used to control the radial growth. 13,14 NWs were made non-intentionally doped ("undoped"), using H 2 S for n-doping, using DEZn for p-doping, and finally with an axially defined p-i-n doped structure. See supplementary material for methods details.…”

Strategies to obtain pattern fidelity in nanowire growth from large-area surfaces patterned using nanoimprint lithography

“…To ensure the compatibility of this procedure with NW growth for solar cell devices, a p-doped NW base was used to ensure good contact with the ptype InP substrate. After 15 s, hydrogen chloride (HCl) was introduced to the growth chamber at a molar fraction of χHCl = 4.6 × 10−5 in order to suppress radial growth [21]. The growth time was 24.5 min, after which the flow of TMIn and HCl was switched off, and the chamber cooled to 300 °C under a PH3/H2 mixture.…”