Orientation-controlled Si1-xGex (0≤ x≤1) films on insulating substrates are essential to achieve high-efficiency solar-cells and highspeed thin-film-transistors. We investigate Al-induced crystallization of amorphous-Si1-xGex/Al-oxide/Al/quartz stacked-structures as a function of Ge-fraction, air-exposure time of Al surfaces, and thicknesses of Al and SiGe films. By tuning interfacial Al-oxide layer thickness, which is controlled by air-exposure time, (100) or (111) Si1-xGex (x < 0.2) layers are selectively formed. However, increase of Ge-fraction significantly enhances the random bulk-nucleation, which results in poly-crystalline Si1-xGe x (x ≥ 0.2) with random-orientations. To enhance interfacial-nucleation at Al/quartz over bulk-nucleation, film-thickness of Al and SiGe are thinned to 50 nm. This achieves (111)-oriented Si 1-xGex films with the whole Ge fractions. This oriented-growth can be explained by the theoretical calculation that (111) SiGe has the minimum surface energy on quartz substrates.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials