Theoretical analysis of a 0.25 μm gate InAlGaP/GaAs heterojunction field effect transistor using ensemble Monte Carlo simulation

Since its invention, designers of heterojunction field effect transistors (HFETs) have been in continuous pursuit of ways to increase the sheet charge density in the channel. An effective way of achieving higher sheet charge density and at the same time improving other device characteristics of an HFET is to use material system with larger conduction band discontinuity. Larger conduction band discontinuity in a double heterostructure HFET also results in a lower output conductance and reduced real space transfer, hence improving the device performance. The fact that the In_0.5(Al_xGa_1-x)_0.5P/GaAs material system has the largest bandgap difference among all III-V semiconductor heterojunctions lattice matched to GaAs makes it extremely attractive for high performance HFET device structures. In this paper a comparison of electron transport properties in a 0.25 μm gate length In_0.5(Al_xGa_1-x)_0.5P/GaAs HFET and a 0.25 μm gate length Al_0.3Ga_0.7As/GaAs HFET is presented based on a two-dimensional ensemble Monte Carlo simulation couple with a Poisson equation solver. In the simulation, realistic conduction band structures are used and major scattering mechanisms are included. The results show that the InAlGaP/GaAs HFET has high drain current density and higher breakdown voltage than the conventional AlGaAs/GaAs HFET, and thus is a potential candidate for high power applications