The structures of single channel heterostructure transistors based on compound semiconductor materials are studied. By means of the simulation tool of Medici. single delta-doping with different structures and doping concentrations are simulated and analyzed. GaAs PHEMT device is one of the most important devices in military and microwave communication applications. Three kinds of PHEMT structures are developed and studied, including modulation-doping AlGaAs/InGaAs pseudomorphic high electron mobility transistors, single delta-doping AlGaAs/InGaAs pseudomorphic high electron mobility transistors, and single InGaP/InGaAs delta-doping pseudomorphic high electron mobility transistors. By means of the simulation tool of Medici, modulation doping and Si delta-doping with different doping profiles are analyzed and simulated. The study results show that double delta-doping layers enhances the uniformity of the distribution of the electric current, and in the meantime , a large operation range, a higher current density, a higher breakdown voltage, a higher density of two dimensional electron gas, and a high transconductance can be obtained. In addition, a undoped spacer layer can be placed between the doped barrier layer and the undoping InGaAs. The results are also show that the larger separation between the carriers and ionized donors the higher the electron mobility, owing to the less coulomb interaction.
