Electrical isolation of p-type GaAs layers by proton bombardment

The electrical isolation of p-type GaAs was investigated using proton ion bombardment at room temperature. Carbon and magnesium doped samples were used to compare the isolation and thermal stability for different acceptor atoms. As the C is manifested like a p-type impurity in the As sublattice site and the Mg in the Ga sublattice site, it was possible to study the influence of the dopant sublattice position. The acceptor concentration for C and Mg doped samples was similar. The evolution of the sheet resistance (R_s) with dose during 400 keV H⁺ ion irradiation was studied. Three regions of R_s versus dose curve are distinguished: (1) R_s enhancement up to ≈2×10⁹ Ω/∉; (2) a plateau starting at a dose of 1×10¹⁴ cm^-2 (named threshold dose of isolation D_th); and (3) decreasing of R_s for doses above 1×10¹⁵ cm^-2 as a result of hopping conduction. The thermal stability of isolation was found to increase with the irradiation dose. In the samples, irradiated to doses⩽D_th, R_s starts to recover at annealing temperatures ≈ 250°C. When the dose is increased to 100D_th, R_s increases with the annealing temperature up to 500°C. For this dose the isolation is maintained up to 650°C and a fast recovery of R_s by 3-4 orders of magnitude occurs at 650-700°C