Reduction of silicon-aluminum interdiffusion by improved semiconductor surface ordering

Aluminum overlayers on highly ordered single-crystal silicon (100) and (111) surfaces in ultrahigh vacuum exhibit characteristic interface widths less than tens of angstroms at room temperature and hundreds of angstroms at 400 °C—orders of magnitude more abrupt than conventionally prepared Al-Si contacts. We demonstrate that surface disorder plays a critical role in promoting Si diffusion into the Al overlayer.