The effect of CdTe deposition temperature on device properties of different TCOs and glass substrates

In this paper, we present our work on devices fabricated using CdTe films deposited by close-spaced sublimation using substrate temperatures in the range of 450° to 620° C. We studied devices prepared on Saint-Gobain soda lime SGG Diamant and Corning 7059 borosilicate glass substrates. We used four types of contact: SnO2:F, ITO, CTO, and Saint-Gobain AZO with and without high-resistivity buffer layers. We used a variety of buffer layers: undoped SnO2, zinc tin oxide (ZTO), and proprietary Saint-Gobain buffer layers. A buffer layer is crucial for devices using CTO and AZO as the front contact. For AZO layers developed by Saint-Gobain, we achieved 9% efficiency without a buffer layer and over 12% efficiency using buffer layers when CdTe films are deposited below 500° C. We used standard current density-voltage and quantum efficiency analysis to determine the device parameters.