Atomic Layer-by-Layer Epitaxy of Silicon and Germanium Using Flash Heating in CVD

Abstract
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 °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 °C. Using these growth controls, resonant tunneling diodes of Ge / Si₁Ge₁(50Å) / Ge(50Å) / Si₁Ge₁(50Å) / 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 °C.