High-Quality AgGaTe₂ Layers on Si Substrates with Ag₂Te Buffer Layers

AgGaTe₂ layers were successfully grown on Si substrates by the close-spaced sublimation method. The Si substrates were confirmed to be etched during AgGaTe₂ layer growth when the layer was grown directly on the substrate. To eliminate melt-back etching, a buffer layer of Ag₂Te was introduced. It was found that the Ag₂Te buffer layer changed into the AgGaTe₂ layer during the growth process, and a uniform AgGaTe₂ layer with an abrupt interface was formed. Both the diffusion of Ga into Ag₂Te and the growth of AgGaTe₂ occurred simultaneously. It was confirmed that uniform AgGaTe₂ layers could be formed without any traces of the Ag₂Te layer or melt-back etching by tuning the growth parameters. A solar cell was also fabricated using the p-AgGaTe₂/n-Si heterojunction. This solar cell showed conversion efficiency of approximately 3%.