Photovoltaic device including a p-n junction and method of manufacturing

A method for forming a photovoltaic structure, comprising:

• providing a substrate structure comprising a transparent conductive oxide (TCO) layer;
• depositing a layer comprising cadmium, selenium, and tellurium over the substrate structure, wherein the step of depositing the layer comprising cadmium, selenium, and tellurium, includes:
• sequentially depositing a CdSe layer over the substrate structure, followed by depositing a CdTe layer over the CdSe layer;
• and
• alloying the layer comprising cadmium, selenium, and tellurium, whereby an absorber layer is formed over the substrate structure, wherein:
• a p-n junction is formed between the absorber layer and the substrate structure, the absorber layer is p-type,
• the absorber layer is composed of cadmium selenide telluride, wherein a concentration of selenium varies through a thickness of the of the absorber layer,
• the absorber layer has higher selenium concentration adjacent to the substrate structure and decreasing through a thickness of the absorber layer, and
• a compositional ratio of Se throughout the absorber layer is less than or equal to about 25 at. %, wherein the compositional ratio of Se is determined by comparing the number of selenium atoms with a total sum of selenium and tellurium atoms in the absorber layer.