Aluminum metallization of III-V semiconductors for the study of proximity superconductivity

Managing the interaction of materials with insertion layers and nonconventional molecular beam epitaxy growth conditions allows for interfaces that are more precise but requires judicious examination of the multiple possible design variables. Here, we show a comparison between As- and Sb-containing insertion layers between Al and two binaries with different group V elements and demonstrate that antimonide layers greatly improve the interface. In addition to depositing Al at extremely slow growth rates onto cold (below 0 degrees C) substrates, the reactivity is particularly minimized with AlSb insertion layers, which improves interface abruptness, preserves the underlying semiconductor layer's crystalline properties, and produces flatter superconductor surfaces.