CRYSTALLINE SILICON THIN-FILMS - A PROMISING APPROACH FOR PHOTOVOLTAICS

In this paper we review the achievements in the field of silicon cryst alline thin film solar cells and correlate these with the different ty pes of growth techniques and substrates. As a starting point we discus s the characteristics of photovoltaic devices based on the use of high ly doped monocrystalline substrates as mechanical carriers for the thi n films. These films are epitaxially deposited from the gas (CVD) or l iquid phase (LPE). The comparison of both techniques is extended to gr owth on defective silicon substrates, i.e., multicrystalline wafers or silicon ribbons. The intrinsic grain boundary recombination activity in the thin films is assessed as a function of the deposition techniqu e. Bulk passivation by hydrogenation considerably improves the recombi nation properties. The optimization of the hydrogen passivation condit ions is looked at in conjunction with the used surface passivation pro cess, This review is completed with the approaches to realize thin fil m cells on nonsilicon substrates, including recrystallization in solid and liquid phases.