Amorphous Si prepared in a UHV plasma deposition system

Although glow discharge decomposition of SiH₄ has been demonstrated to yield a-Si:H films with potential for large area device applications, the a-Si:H films often have high impurity level (～ 10¹⁹t- 10²⁰/cc). Moreover, cross contamination of dopants at interfaces between differently doped layers is a problem. Since both issues may be the key to improving material quality, a UHV plasma deposition systems has been built to address them. By controlling all sources of contaminants such as chamber walls, gas lines and gas bottles, the impurity levels have been significantly lowered to ～10¹⁷?10¹⁸/cc. In addition, sharp interfaces between differently doped layers are obtained, which allow the preparation of multilayer structures.