ATOMIC LAYER-BY-LAYER EPITAXY OF SILICON AND GERMANIUM USING FLASH HEATING IN CVD

Atomic layer-by-layer epitaxy control of Si and Ge in flash-heating CVD using SiH4 and GeH4 gases was investigated. Self-limiting SiH4 reaction on the Ge surface results in Si atomic-layer formation at substrate temperatures below 300 degrees C even without the flash heating. In the case of Ge growth, by increasing the flash light intensity and the GeH4 partial pressure, Ge atomic-layer growth on the wet-cleaned Si(100) was achieved with a single flash shot at 275 degrees C. Using these growth controls, resonant tunneling diodes of Ge/Si1Ge1(50 Angstrom)/Ge(50 Angstrom) /Si1Ge1(50 Angstrom)/Ge, in which the Si1Ge1 layers were formed by alternately depositing single atomic-layers of Si and Ge, were fabricated, and clear negative resistance in the current-voltage characteristic was observed at 10 K. The current peaks were expected to be assigned to a hole resonant tunneling via light-hole bound state in the Ge quantum well. This fact suggests that the diode structure has abrupt Si1Ge1/Ge interfaces by employing a low-temperature atomic layer-by-layer growth process below 300 degrees C.