Low-temperature annealed ohmic contacts to Si-doped GaAs and contact formation mechanisms

Using nonferromagnetic contact materials, Au(x nm)/Ge(y nm)/Pd(z nm) structures (where x, y, and z are the thicknesses of Au, Ge and Pd layers, respectively) are fabricated on Si-doped GaAs and studied as a function of x, y and z and n-type substrate doping density and annealing temperature to characterise them as ohmic contacts. The study shows that the structure with x = 100, y = 40 and z = 10, annealed at 180 °C for 1 h, contacts n-type GaAs more reliably with the low contact resistance. Using Rutherford backscattering spectrometry, contact formation mechanisms are also studied.