Advanced Modeling Concepts and Material Considerations for Iii-V Heterostructure Electron Devices on Gallium Arsenide Substrates

A survey of semiclassical nonstationary charge transport models for submicron electron devices has been presented, and utility of the models has been discussed. A three-valley hydrodynamic model with improved collision terms has been proposed as a reliable and faster alternative to Monte Carlo simulations for device optimization purposes. The response of the model to rapid time and space variations of large electric fields has been found to be in excellent agreement with that of ensemble Monte Carlo simulations. Status of the heterostructure III-V electron device technology on GaAs substrates has been discussed. Electron transport properties of rm Ga_{0.51 }In_{0.49}P, which is a promising alternative to rm Al_{x}Ga _{1-x}As, have been calculated. A comparison of the steady-state and transient transport in rm Ga_{0.51}In_ {0.49}P and rm Al_ {0.3}Ga_{0.7}As has been demonstrated. The potential of GalnP for electron device applications has been evaluated. Material and device characterization results of metalorganic chemical vapor deposition grown GalnP/GaAs heterojunction bipolar transistors have been presented. X -ray diffraction measurements have shown lattice matched films, and electrochemical C-V profiling yielded excellent doping and thickness control in the device layers. A current gain as high as 100 has been achieved at a collector current density of 711 A/cm^2. A model-based comparison of the frequency responses of rm Al_{0.3}Ga_ {0.7}As/GaAs and rm Ga_ {0.51}In_{0.49}P/GaAs single and double heterojunction bipolar transistors yielded comparable speed performance. Collector transport has been simulated by using the proposed three-valley hydrodynamic model. Base-collector depletion layer transit times and cutoff frequencies have been evaluated for devices with various collector structures. Speed-power trade-off and optimum collector doping density have been discussed. As an alternative to GaAs and related compounds, the feasibility of high mobility, low bandgap antimonides for future ultra-fast electron device applications on GaAs substrates has been investigated. Experimental and theoretical transport studies on lattice-mismatched rm InSb_{0.7}As_{0.3} layers grown on GaAs substrates, and a semi-quantitative analysis of the effects of lattice mismatch on carrier transport properties have been presented. Possible device related problems have been addressed.