Electronic properties of highly P and B doped thin Si layers grown by ECR-CVD

Thin Si films strongly doped with P and B are grown at 325 degrees C by ele ctron cyclotron resonance chemical vapor deposition (ECR-CVD) on quartz sub strates and Si wafers. Films deposited on quartz are microcrystalline. By a n analysis of Hall effect data it is shown that the electrical transport in these films is controlled by potential barriers at grain boundaries. Using a simple barrier-limited transport model it is found that the effective in terface defect density Q(it) increases with the doping level N-d,N-a, follo wing a power law. A study of electron spin resonance shows that the in-grai n mobility of electrons is much higher than the Hall mobility. At high dopi ng levels the films grew epitaxially on Si substrates. Such films are used as emitter layers in solar cell structures and efficiencies of 14% are demo nstrated. (C) 2000 Elsevier Science S.A. All rights reserved.