Development of STM operational in a plasma and its application to a control of plasma materials surface processing on an atomic scale

在这个项目中，我们首次尝试开发用于等离子体环境下的扫描隧道显微镜(STM)。该装置由一个STM系统和一个射频(RF)(430 MHz)等离子体产生系统组成，该系统安装在带有旋转泵的真空室中。一种分辨率为10毫微微安培的特殊放大器。隧道电流测量最高可达1KV。为了防止来自等离子体的噪声电流，铂-Ir探头尖端使用溶胶凝胶法涂上环氧脂和中空玻璃，但在大约3微米的尖端周围除外。在常规辉光等离子体条件下，经过1800秒的等离子体曝光，等离子体产生的噪声电流小于0.1nA。利用该装置，在射频、低压(0.3Tbrr)空气辉光等离子体下获得了高定向热解石墨(HOPG)的纳米级台阶结构和原子图像。我们还讨论了STM提示对于成功的、现实的“原位”观察的作用。

In this project, we performed the first attempt at the development of a scanning tunneling microscope (STM) for use under a plasma environment. The apparatus consists of an STM system and a radio-frequency (rf) (430MHz) plasma generation system housed in a vacuum chamber with a rotary pump. A special amplifier with a resolution of 10 femtoamp. up to 1kV is employed for tunneling current measurements. To prevent noise current from the plasma, the Pt-Ir probe tip is coated with epoxy grease and insulated glass using the sol-gel method except around its apex of about 3 mum. Under the conventional glow-plasma condition, the noise current from the plasma was deduced to be less than 0.1 nA during plasma exposure for 1800 sec. Using this apparatus, the step structure on a nanometer scale and atomic image of highly oriented pyrolytic graphite (HOPG) were obtained under rf, low-pressure (0.3 Tbrr) air glow plasma. We also discussed the role of the STM tip for successful, realistic "in situ" observation.