Relationship between implantation damage and electrical activation in gallium arsenide implanted with Si+

The relationship between implantation damage and electrical activation has been investigated in GaAs implanted with 100-keV 30Si+ to doses of 5×1013/cm2 and 2×1014/cm2, using low and moderate beam currents at room temperature (RT) and at slightly elevated temperatures. For a given Si+ dose, the damage, measured by ion channeling immediately after implantation, was varied by more than a factor of 2 over the range of conditions studied. A strong negative correlation was established between this damage and the electrical activation obtained after high-temperature annealing, i.e., an increase in the initial damage led to a decrease in the sheet-carrier concentration. The results demonstrate a scheme for increasing the sheet-carrier concentration beyond that typically obtained for high-dose Si in GaAs, namely, by using a slightly elevated implant temperature (∼90 °C for a beam current of 1 μA/cm2). In addition, the initial damage is shown to consist of two components; one that is stable at RT and another that is not. The sheet-carrier concentration was found to be affected only by that component of the damage that is stable at RT, although both components were reduced by increasing the implant temperature or by reducing the dose rate.