Hot-wire produced atomic hydrogen: effects during and after amorphous-silicon deposition

The role of hot-wire atomic hydrogen during a-Si:H deposition is elucidated by investigating hydrogen diffusion into and within hot-wire deposited a-S i:H films. We exposed device-quality a-Si:H layers to atomic hydrogen in or der to mimic the atomic hydrogen flux during deposition. Initially, exposur e of as-deposited a-Si:H films leads to an enhancement of the hydrogen conc entration by a factor of 2. A higher wire temperature or a longer duration of the atomic hydrogen exposure etches the silicon layer. The temperature o f the films during these treatments was below the deposition temperature. D eposition of double layers which incorporate either H or D, shows considera ble diffusion taking place at the substrate temperature which is usually ap plied for hot-wire a-Si:H layers in devices. The observation of these effec ts, the high atomic hydrogen flux and the high diffusion coefficient, indic ate the important role of atomic hydrogen during hot-wire deposition. (C) 2 001 Elsevier Science B.V. All rights reserved.