ABSTRACT
Wafer-bonding and film transfer have been developed in the microelectronic industry and these techniques are presently used to make silicon-on-insulator (SOI) structures. They are also of interest for photovoltaic cells and many studies have been done to develop thin-film cells based on film transfer [1-9]. They have also been studied to make multi-junction cells [10, 11]. In this chapter, we will describe recent developments in film transfer which could be of interest for multi-junction photovoltaic cells. Presently, multi-junction cells are made either by direct epitaxy onto a substrate or by mechanical stacking. In cells processed by epitaxy, the current is common to all cells and requires precise matching of the cells. Mechanically stacked multi-junction cells do need current matching between the cells and offer more flexibility for the choice of gaps (see figure 12.1).
