Investigation of ion bombardment of GaAs-based HBTs with InGaAs capping layer

We have investigated He/sup +/-ion bombardment on a lattice-matched multi-layer In/sub 0.5/Ga/sub 0.5/P/GaAs HBT structure with InGaAs capping layer. A single energy implantation of helium-ion was tested on this structure at 600 keV with a dose of 3/spl times/10/sup 15/ cm/sup -2/ at room temperature. Post implant annealing was performed for 60 s from 50 to 600/spl deg/C. A maximum achievable sheet resistance of 2/spl times/10/sup 8/ /spl Omega//sq was recorded for the GaAs-based base and collector layers and 3/spl times/10/sup 5/ /spl Omega//sq for the emitter-capping layer. Analysis shows that isolation of the whole HBT structure is affected due to the introduction of a narrow-bandgap InGaAs capping layer.