Electrical isolation of n-type InP by ion bombardment: Dose dependence and thermal stability

The increasing of the sheet resistance (R-s) of n-type conductive InP layers during proton irradiation and the stability of the formed isolation during post-irradiation annealing were investigated. It was found that the threshold dose (D-th) to convert the conductive layer to a highly resistive one is directly proportional to the original sheet electron concentration (n(s)) and inversely proportional to the estimated concentration of In atoms substituting P atoms in the P sublattice, caused by replacement collisions. From the experimental data, one infer that the antisite defects and/or their related defect complexes formed by the replacement collisions are the carrier trapping centers. A time dependence of the R-s was observed after each irradiation step to doses of congruent to D-th and higher. The thermal stability of the isolation is limited to temperatures lower than 200 degreesC, irrespective of the irradiated dose and of n(s). (C) 2001 Elsevier Science B.V. All rights reserved.