Beryllium ion implantation in GaAsSb epilayers on InP | CU Experts

Beryllium ion implantation was used to form high acceptor concentrations in GaAs1−xSbx (0.47≤x≤0.49) epilayers on semi-insulating InP substrates. Two implant doses were tested: Q0=5×1014 cm−2 and Q0=1×1015 cm−2 at an implant energy of E=50 keV. Electrochemical profiling and secondary-ion-mass spectrometry (SIMS) results confirm acceptor concentrations of NA≥1×1019 cm−3 and NA≥2×1019 cm−3 within 1000 Å of the GaAs1−xSbx surface for the lower and higher implant dose, respectively. These results provide a p+ surface layer for low-resistance ohmic contact to GaAsSb-based devices. Optical microscopy and SIMS demonstrate rapid thermal anneal (RTA) temperature limits of T=650 °C for Q0=5×1014 cm−2 and T=600 °C for Q0=1 ×1015 cm−2. The temperature limitation is imposed by destabilization of the GaAs1−xSbx surface through Ga sputtering during implantation, and Ga and As outdiffusion during RTA.

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