Formation of High-Quality Si/CoSi2/Si Double Hetero-Structures by Self-Aligned and Two-Step Molecular Beam Epitaxy

The formation and application of Si/CoSi2/Si double heterostructures are comprehensively studied. A high-quality double heterostructure is formed by two-step molecular beam epitaxy of the Si over layer, i.e., low -temperature growth followed by high-temperature growth. The interfaces between CoSi2 and Si observed by cross-sectional transmission microscopy are atomically abrupt and smooth. In addition, a new fine patterning method of CoSi2 films using self-aligned and selective growth is developed. Finally, permeable base transistors (PBT) with high performance (gm=50 mS /mm) are fabricated using these new techniques.