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

The increasing of the sheet resistance (R-s) of n-type conductive InP layer s during proton irradiation and the stability of the formed isolation durin g post-irradiation annealing were investigated. It was found that the thres hold 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 sub stituting P atoms in the P sublattice, caused by replacement collisions. Fr om the experimental data, one infer that the antisite defects and/or their related defect complexes formed by the replacement collisions are the carri er trapping centers. A time dependence of the R-s was observed after each i rradiation step to doses of congruent to D-th and higher. The thermal stabi lity of the isolation is limited to temperatures lower than 200 degreesC, i rrespective of the irradiated dose and of n(s). (C) 2001 Elsevier Science B .V. All rights reserved.