Step structure of arsenic-terminated vicinal Ge (100)

Germanium (100) crystals, 9 degrees off-axis towards the [011] were exposed to 2.0 Torr of tertiarybutylarsine and 99.0 Torr of hydrogen at 650 degree s C, then heated to between 450 and 600 degrees C in vacuum or H-2. The res ulting surfaces consist of narrow dimer-terminated terraces, with (1X2) and (2X1) domains, that are separated by steps between one and eight atomic la yers in height. The distribution of (1X2) and (2X1) domains changes with te mperature, exhibiting a pronounced maximum in the (1X2) fraction at 510 deg rees C. These results suggest that the arsenic passivation of germanium is a critical step in gallium arsenide heteroepitaxy. (C) 1999 American Instit ute of Physics. [S0021-8979(99)01503-0].