CONTROL OF FREE RADICALS FOR CONSTRUCTION OF MESOSCOPIC STRUCTURES OF MATERIALS

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The real time control of the mososcopic structures of semiconductors was made by means of free radicals under the in situ observation with spectroscopic ellipsometry, STM (AFM) in an aqueous solution, FTIR-ATR,etc.Followings are the outstanding findings resulted in : (1) High quality hydrogenated amorphous silicon with the gaps from 1.55eV to 2.10eV was fabricated by controlling the medium range structures with the aid of free radicals during the growth, so called "Chemical Annealing". (2) High quality polycrystalline silicon thin films were grown on glass substrate under control of the surface reaction under the in situ observation with spectroscopic ellipsometry. (3) Novel technique termed the high fluidity CVD was developed by controlling surface reaction of free radicals under the observation with FTIR-ATR for making fine patterns on Si wafer. (4) A diagnostic study was carried out on the free radicals generated in plasma for the aim of making high quality amorphous silicon. Consequently, a-Si : H films showing high carriers mobility were achieved by the precise control of ions impinging on the growing surface. (5) The mechanism in atomic scale was revealed for the chemical etching of Si (111), (001) with HF or NH4F solution under the real time observation with STM (AFM) under controlling the electrochemical potentials. (6) Silicon nanocrystalline particles were fabricated by controlling hydrogen plasma and were manipulated with a AFM.Some quanmsize effets such as a single electron tunneling and the emission of visible light were practically observed in the particles.