Hirokazu Ohtoshi

Preparation of Polycrystalline Silicon by Hydrogen-Radical-Enhanced Chemical Vapor Deposition

The preparation of both amorphous and epitaxial crystalline silicon films by Hydrogen-Radical-Enhanced Chemical Vapor Deposition at variable hydrogen flow rates is discussed. The feasibility of fabricating polycrystalline Si at high growth rates and a low substrate temperature is demonstrated. Finally, the n-type characteristics of PH3 doping and p-type characteristic for BF3 doping are examined in terms of the conductivity and the Hall mobility of the films.

The Role of Hydrogen Radicals in the Growth of a-Si and Related Alloys

A new method of the preparation of a-Si and its alloys is proposed. The role of atomic hydrogen in the growth of a-Si:H:(F) films by the glow-discharge of a mixture of SiF4 and H2 is clarified. Amorphous Si:H:(F) films have been prepared in a plasma-free environment by employing long-lifetime radicals, i.e., atomic hydrogen and SiFn radicals. Highly photoconductive a-Si:H:(F) films and related alloys, viz. a-SiGex:H:(F) and a-SiCx:H:(F), have been obtained at high deposition rates with the result that each radical is controlled independently.