Catalyst- and template-free low-temperature in situ growth of n-type CdS nanowire on p-type CdTe film and p-n heterojunction properties.

Ligang Ma,Fengming Zhang,Hongling Cai,Wenchao Liu,Xiaoshan Wu

doi:10.1038/srep38858

Abstract

CdS is an important semiconductor used in optoelectronic devices. Simple techniques for growing CdS nanostructures are thus essential at a low cost. This study presents a novel method for growing single-crystal n-type CdS nanowires on p-type CdTe films by thermal annealing in an H2S/N2 mixed gas flow, which does not require the help of a catalyst or template. The formation process and growth mechanism of the nanowires are investigated. Well-dispersed whiskerlike CdS nanostructures are obtained at an appropriate annealing temperature and duration. We suggest that the stress-driving mechanism of nanowire formation may contribute to the growth of CdS nanowires, and that the evaporation of Te through the boundaries of the CdS grain seeds plays an important role in the sustainable growth of nanowire. In addition, CdS/CdTe heterojunction device is fabricated on Mo glass. The I-V characteristic of the heterojunction in dark shows typical rectifying diode behavior. The turn-on voltage can be regulated by annealing conditions. Meanwhile, the obvious photovoltaic effect is obtained on the in situ growth heterojunction prepared at low annealing temperature. Hence, this is a new fabricated method for CdTe-based materials in the field of energy conversion.

Highlights

Of obtaining a high yield of high-quality morphology-tunable CdS nanowires needs to be put forward
The X-ray photoelectron spectroscopy (XPS) measurement indicates that nanoparticles are mostly the A1 (Te) particle, and CdS film is formed at this time
Simple, and low-temperature method for the synthesis of large-scale and high-density single-crystal hexagonal wurtzite structure CdS nanowires based on CdTe film

Summary

Introduction

Of obtaining a high yield of high-quality morphology-tunable CdS nanowires needs to be put forward. Novel method of fabrication CdS nanowire structures has been found, such as catalyst-free template method[22], in situ growth using pulsed laser deposition on low temperature[23], and assisted synthesis method[24], and so on. We demonstrate for the first time a novel and simple approach to the in situ growth of CdS nanowires on a CdTe film surface via annealing in an H2S/N2 mixed flow at temperatures as low as 450 °C. This low-cost, low-temperature, easy-to-control process requires neither a catalyst and template nor organic solvents and a solution process. The substrate we used is a p-type CdTe film, and combining with the grown n-type CdS nanowires, a promising low dimension CdTe based device is fabricated

Methods

Results

Conclusion