材料科學與工程 材料物理與化學，外文文獻翻譯及原文

MICROSTRUCTURE AND MECHANICAL PROPERTIESOF ALUMINIUM BACK CONTACT LAYERS

ABSTRACT:
The overall demand to reduce solar energy costs gives a continuous drive to reduce the thickness ofsilicon wafers. Handling and bowing problems associated with thinner wafers become more and more important, asthese can lead to cells cracking and thus to high yield losses. In this paper the microstructure and mechanicalproperties of the aluminium on the rear side of a solar cell are discussed. It is shown that the aluminium back contacthas a complex composite-like microstructure, consisting of five main components: 1) the back surface field layer;2) a eutectic layer; 3) spherical (3 - 5 μm) hypereutectic Al-Si particles surrounded by a thin aluminum oxide layer(200 nm); 4) a bismuth-silicate glass matrix; and 5) pores (14 vol.%). The Young’s modulus of the Al-Si particles isestimated by nanoindentation and the overall Young’s modulus is estimated on the basis of bowing measurements.These results are used as input parameters for an improved thermomechanical multiscale model of a silicon solar cell.