Figure 1: Clean H terminated Si 100 surface 100nm*100nm
Sample bias: -3V; Current:-0.45nA; Scanning angle:45 deg; Integral gain: 200 m/As; Pixel: 1024*1024; Scanning speed: 476 nm/s
Preparing atomically clean samples are a primary requirement for developing patterned dopant devices based on hydrogen resist lithography. The samples from this study are used to develop moderately low temperature silicon overgrowth to ensure epitaxial Si on Si growth. The overall process involves, hydrogen lithography, phosphine dosing and subsequent dopant activation, and then silicon overgrowth to encapsulate the patterned devices. Quality Si epitaxial overgrowth is essential to good local electronic properties for the encased atomic-scale phosphor-based donor devices. The silicon (100) samples ( 4 mm x 10 mm ) were first chemically cleaned using an RCA Piranha recipe and HF dipped to passivate the surface. The samples were then load locked into a UHV system for thermal processing. Thermal processing includes a couple of 1200 °C flashes (maintaining low -10 Torr pressure all the time) and a 1050 °C anneal for a few hours. The samples were then hydrogen terminated in situ with an atomic hydrogen source and moved to the Pan Scan STM chamber for RT imaging using the recent new design RHK all metal tip holder. W polycrystalline tips were used.
Images and data graciously provided by Richard Silver, NIST.
RHK PanScan Microscope
RHK Technology Control System