Refinements of fabrication processes in sputtered double-layer ITO/InP solar cells

Abstract

A two-layer fabrication technique developed to avoid surface degradation in sputtered indium tin oxide (ITO)/indium phosphide (InP) solar cells, initially provided insight into junction formation mechanisms, and has now been further refined to provide gains in efficiency. A critical parameter is the deposition rate of the first layer (indium tin) onto the InP surface, and it was found that this layer should be deposited at greater than 1Ås−1. A major problem was the series resistance and, to improve this, extensive experimental work was carried out into varying the post-deposition annealing procedure of the second film, the ITO layer. Finally, a preliminary study of devices with the first layer electron-beam evaporated was carried out and a comparison between sputtered and electron-beam devices confirmed previous ideas on junction formation mechanisms.