Substrate temperature dependence of electrical conduction in nanocrystalline CdTe: TiO2 sputtered films

S. N. Sharma, S. M. Shivaprasad, Sandeep Kohli, A. C. Rastogi

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

TiO2 thin films with high volume fraction (∼50-70 %) of CdTe nanoparticles were prepared by radio frequency (rf) magnetron sputtering from a composite TiO2:CdTe target. With increase in substrate temperature Ts from room temperature (RT ∼ 300 K) to 373 K, a transition from an ordered structure exhibiting metallic-type conduction to a disordered structure exhibiting nonmetallic -type conduction was observed for annealed nanocrystalline CdTe:TiO2 films. The annealed RT-deposited films showed a large coalescence of distinct islands (size ∼0.3-0.7 μm) mainly of Cd and CdTe, and as result, a 3D network was realized. For metallic regime films, electrical conduction is essentially due to electrical percolation through Cd/CdTe crystallites embedded in an amorphous TiO2 matrix. However, the annealed high Ts films consisted of noncoalescent, small islands (size ∼0.15-0.3 μm) of Cd and CdTe embedded in amorphous TiO2 matrix. Here, the conduction is essentially by hopping mechanism via thermally activated tunneling.

Original languageEnglish
Pages (from-to)1739-1749
Number of pages11
JournalPure and Applied Chemistry
Volume74
Issue number9
DOIs
StatePublished - 1 Sep 2002
Externally publishedYes

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