CONTROL OF FREE RADICALS FOR CONSTRUCTION OF MESOSCOPIC STRUCTURES OF MATERIALS

利用椭圆偏振光谱、水溶液中的扫描隧道显微镜(AFM)、傅立叶变换红外光谱(FTIR-ATR)等手段对半导体摩尔微观结构进行了实时控制。主要研究结果如下：(1)利用生长过程中的自由基控制中程结构，获得了高质量的氢化非晶硅，其间隙为1.55 eV~2.10 eV，即所谓的“化学退火法”。(2)通过椭圆偏振光谱原位观察，控制表面反应，在玻璃衬底上生长出高质量的多晶硅薄膜。(3)在FTIR-ATR观察下，通过控制自由基在硅片上的表面反应，发展了高流动性化学气相沉积在硅片上形成精细图形的新技术。(4)为了制备高质量的非晶硅，对等离子体中产生的自由基进行了诊断性研究。因此，通过精确控制离子入射到生长表面，获得了具有高载流子迁移率的a-Si：H薄膜。(5)利用原子力显微镜(STM)对电化学电位控制下的扫描隧道显微镜(STM)进行实时观察，揭示了用HF或NH4F溶液对Si(111)、(001)进行化学刻蚀的原子尺度机理。(6)通过控制氢等离子体制备了硅纳米晶颗粒，并用原子力显微镜对其进行了操纵，在颗粒中观察到了单电子隧穿和可见光发射等量子尺寸效应。

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.