An approach to providing a method of forming a dopant junction in a semiconductor device. The approach includes performing a surface modification treatment on an exposed surface of a semiconductor layer and depositing a dopant material on the exposed surface of the semiconductor layer. Furthermore, the approach includes alloying a metal layer with a dopant layer to form a semiconductor device junction where the semiconductor layer is composed of a Group III-V semiconductor material, the surface modification treatment occurs in a vacuum chamber to remove surface oxides from the exposed surface of the semiconductor layer, and each of the above processes occur at a low temperature.