Electrical isolation of GaAs by light ion irradiation damage

The electrical isolation in GaAs formed by light ion irradiation was system atically investigated. The threshold dose (D-th) to convert a conductive la yer to a highly resistive one is found to correlate with the doping level o f the layer to be isolated and with the mass of the ion used. From the anal ysis of the obtained data it was deduced that the carriers are trapped by t he antisite defects and/or their related defect complexes created in the co llision cascades. The thermal stability of the isolation, i.e. the temperat ure range for which the sheet resistance (R-s) is maintained at approximate to 10(9) Omega/square, was found to be dependent on the ratio of the carri er trap concentration to the original carrier concentration. The temperatur e of approximate to 650 degrees C is the upper limit for the thermal stabil ity. A procedure is proposed for the design of the irradiation parameters t o obtain improved thermal stability.