No abstract

In an attempt to identify the factors which limit the performance of InP solar cells made by the closed -ampoule diffusion of sulphur into p -type InP substrates, and in order to optimize the fabrication process, we have done a detailed analysis of the InP surface and of the diffused emitter region using XPS, Auger, SEM and EDAX for diffusion temperatures of 600, 625, 650, 675, 700 and 725 °C for a fixed diffusion time of 3 hours, and diffusion times of 1, 2, 3, and 4 hours for a fixed temperature of 675 °C. In this paper, we present the results of this analysis, showing how the morphology and chemical composition of the InP surface layer changes with the diffusion temperature and identifying the possible mechanisms which limit the photocurrent and the open circuit voltage of solar cells fabricated using the closed-ampoule diffusion process.

In an effort to optimize the processing of n+p and p+n InP structures made by thermal diffusion, so as to be able to achieve high efficiency InP solar cells by this method of junction formation, we have developed a number of new etchants and electrolytes for chemical or electrochemical revealing of surface and deep defect densities (EPD, precipitates and diffusion induced dislocations). These new chemical solutions are not only much more convenient to use for large structural defect density revealing of InP substrates and structures as compared to other techniques, such as transmission electron microscopy, but they also have higher resolution and accuracy.