CONTROL OF FREE RADICALS FOR CONSTRUCTION OF MESOSCOPIC STRUCTURES OF MATERIALS

在椭偏光谱、水溶液中STM （AFM）、FTIR-ATR等原位观察下，利用自由基对半导体的微观结构进行了实时控制。主要研究成果如下：(1)利用生长过程中自由基的辅助控制中范围结构，即化学退火，制备出了间隙在1.55 ~ 2.10eV之间的高质量氢化非晶硅。(2)利用椭偏光谱原位观察，在控制表面反应的条件下，在玻璃衬底上生长出了高质量的多晶硅薄膜。(3)在FTIR-ATR观察下，通过控制自由基的表面反应，开发了高流动性CVD技术，用于在硅片上制作精细图案。(4)为制备高质量非晶硅，对等离子体中产生的自由基进行了诊断研究。因此，通过精确控制撞击生长表面的离子，可以获得具有高载流子迁移率的a-Si: H薄膜。(5)在电化学电位控制下，通过STM （AFM）实时观测，揭示了HF或NH4F溶液化学蚀刻Si(111),（001）的原子尺度机理。(6)通过控制氢等离子体制备硅纳米晶颗粒，并用原子力显微镜对其进行处理。在粒子中实际观察到一些量子效应，如单电子隧穿和可见光的发射。

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.