New directions in amorphous and thin film silicon materials and devices

Abstract

We review the continuing improvements in amorphous, microcrystalline and thin film crystalline Si materials and devices over the past few years. Many of these improvements have resulted from asking fundamental questions regarding how the material is grown, what its structure is, and how to make it better. For amorphous materials, significant changes in growth chemistry have resulted in reductions in H content in some cases, changes in localized H bonding, changes in microstructure, and in reductions in microstructural voids in the material, thereby leading to improved stability and performance. By achieving a transition from amorphous to microcrystalline phase, it has been possible to make high quality, small grained crystalline Si films with naturally passivated grain boundaries. The high quality of microcrystalline films have allowed one to make high performance solar cells in these materials. Finally, the achievement of super-back reflectors and growth of high quality thin film crystalline Si films on ...