SIMULATION OF BERYLLIUM DIFFUSION IN THE BASE LAYER OF INGAAS INP HETEROJUNCTION BIPOLAR-TRANSISTORS/

To explain the observed beryllium diffusion profiles in the InGaAs bas e layer of InGaAs/InP heterojunction bipolar transistors, the most bas ic form of Frank-Turnbull mechanism is proposed and implemented in a c omputer simulation program. A double profile is obtained which may be explained by the reduction in the vacancy concentration in the bulk of the crystal below its equilibrium concentration. Calculated profiles are computed and compared with our experimental profiles and with othe r beryllium diffusion profiles available in InGaAs. Some parameters su ch as diffusion time, diffusion coefficients, concentrations and vacan cy bulk generation are investigated. The effect of V/III ratio on post -growth annealing profiles is also simulated. The point defect concent ration in epitaxial layers during beryllium diffusion in InGaAs is dis cussed.