Growth and Characterization of InP Nanowires with InAsP Insertions

Maria Tchernycheva, George E. Cirlin, Gilles Patriarche, Laurent Travers, Valery Zwiller, Umberto Perinetti, and Jean-Christophe Harmand.

Nano Letters 2007 Vol.7, No.6, 1500-1504.

 

Purpose of the study

Fabricate InP nanowires with embedded InAsP insertions by Au-assisted molecular beam epitaxy.

Methods

InAsP insertions in InP nanowires were fabricated by Au-assisted molecular beam epitaxy(MBE) growth techniques. The growth temperature affects the nucleation on the nanowire lateral surface. It is therefore possible to grow the wires in two steps: to fabricate an axial heterostructure (at 420℃), and then cover it by a shell (at 390℃).

 

Key findings

1.     The wire shape was shown to change from pencil-like for 390℃growth to cylindrical for 420℃ growth.

2.     The InAsP alloy composition could be varied between InAs_0.35P_0.65 and InAs_0.5P_0.5 by changing the As to P flux ratio.

3.     The presence of InP shells around the InAsP insertions is important to observe efficient photoluminescence(PL) emission. When a shell is present, the InAsP insertions show room-temperature photoluminescence peaked in the 1.2-1.55µm wavelength range. If the axial heterostructure has no shell, luminescence intensity is drastically reduced.

4.     The micro-PL from isolated nanowires shows narrow lines with a full width at half-maximum(FWHM)  as small as 12µeV.

 

Important definitions

1.     Molecular beam epitaxy(MBE)-MBE is one of several methods of depositing single crystals, which takes place in high vacuum or ultra high vacuum. The most important aspect of MBE is the slow deposition rate (typically less than 1000 nm per hour), which allows the films to grow epitaxially.