Paper Title
Kinetics and Thermal Stability of A-Si: H/Age: H Multilayers Used in Solar Cells

Abstract
Multilayers of a-Si:H/a-Ge:H are used as a new type of narrow band gap materials for amorphous silicon�based solar cells. High efficiency solar cells are necessary to convert solar energy to electrical energy at low cost until. Nano-multilayers (NMLs) of a-Si:H/a-Ge: H were prepared at 200◦C by alternating deposition from SiH4 and GeH4 plasmas in a computer-controlled four chamber glow-discharge deposition system with capacitively coupled diode reactors [1,2]. X ray diffraction and scanning electron microscope (SEM) were used to study the structural changes. The electrical conductivity and structural changes during annealing of the MLs have been investigated. The annealed multilayers exhibit surface and bulk degradation with formation of bumps and craters. The electrical measurements results reveal that the increase of electrical conductivity with increasing the annealing temperature and/or time is partially due to formation of H bubbles in the Ge layers and partially due to crystallization effects. On the other hand it was found that the activation energy of crystallization deduced from the annealing time dependence of the conductivity using Avrami's equation is compositional dependent. Keywords- a-Si:H/a-Ge: H multilayers, structure, electrical conductivity, crystallization, Avrami's equation