Self-Catalyzed CdTe Wires.

Tom Baines,Leon Bowen,Jonathan Major,Oliver Hutter,Giorgos Papageorgiou,Ken Durose

doi:10.3390/nano8050274

Abstract

CdTe wires have been fabricated via a catalyst free method using the industrially scalable physical vapor deposition technique close space sublimation. Wire growth was shown to be highly dependent on surface roughness and deposition pressure, with only low roughness surfaces being capable of producing wires. Growth of wires is highly (111) oriented and is inferred to occur via a vapor-solid-solid growth mechanism, wherein a CdTe seed particle acts to template the growth. Such seed particles are visible as wire caps and have been characterized via energy dispersive X-ray analysis to establish they are single phase CdTe, hence validating the self-catalysation route. Cathodoluminescence analysis demonstrates that CdTe wires exhibited a much lower level of recombination when compared to a planar CdTe film, which is highly beneficial for semiconductor applications.

Highlights

Due to their unique properties, semiconductor nano and microwires have attracted a lot of interest for optoelectronic devices
The preferable implementation for CdTe wires in a solar cell structure is via the “substrate” cell structure [17], wherein the CdTe component must be deposited on top of a suitable back contact medium
For substrate CdTe devices the back contact material is Mo as its thermal expansion coefficient is close to that of CdTe and its use is well established for other thin film technologies such as Copper Indium Gallium Selenide (CIGS) and Copper Zinc Tin Sulfide (CZTS) [18,19], there are some issues with regards to generation of an Ohmic contact [17]

Summary

Introduction

Due to their unique properties, semiconductor nano and microwires have attracted a lot of interest for optoelectronic devices. Prior work on catalyst free CdTe wires primarily consists of two approaches (i) a solution based method grown via a solution-liquid-solid (SLS) mechanism [13], or (ii) a template assisted electrodeposition route using, for example, an aluminum oxide film as the template [14]. Both of these techniques have their disadvantages; they often require the use of solvents like oleylamine or complex patterning steps for the template layers. Wires produced by solution based methods are often difficult to incorporate into device structures as many applications require vertically aligned wires projecting from the surface of the substrate [15]

Methods

Results

Conclusion