Numerical Simulation Of High-speed InP Devices

With wide bandgap,high drift velocity and good conductivity, InP based HBTsobtain the higher current gain and better frequency,so they have been the importantdevices that realize the high speed circuits,microwave millimeter-wave circuits andoptical communication systems.Because device simulation can shorten the productioncycle,reduce the production cost and give device intuitive drawing, accurate numericalsimulation model of InP HBT has very important instruction meaning for experimentand process optimization.In this paper we adoped two-dimensional hydrodynamic model to simulate thecharacteristics of the InP/InGaAs double heterojunction bipolar transistors(DHBTs)with the simulation software ISE TCAD.Besides this,the model also includes mobilitymodel,generation-recombination model,energyband model,thermionic emission currentmodel and tunneling model.This model can well describe the carriers transport ofheterojunction devices and speed overshoot of material.We demonstrated the structure principle and excellent characteristics of the InPDHBT and simulate the DC,AC and breakdown characteristics. The maximum DC gainis65. The common emitter breakdown voltage is bigger than7V. The current gain cutofffrequency fTis154GHz and the maximum oscillation frequency fmaxis253GHz.Research indicates that thermionic emission model and tunneling model havethe important effect on the carriers transport over the heterojunction interface with theconduction discontinuity and valence discontinuity.We can use graded base,δ-dopinglayer and superlattice structure to reduce the conduction discontinuity and then avoidthe current blocking effect.Compare simulated and measured data and shows goodagreement which verify the correctness of the model in order to lay the foundation forthe further studying of the device experiments.