Effect of Impurity Concentration and Biasing-Current Density on the Performance of a New DDR Heterojunction Impatt Diode

Abstract

Large-signal analysis has been carried out for a new DDR Heterojunction Impatt diode to study the effect of biasing-current density and impurity concentration of the power and efficiency of the device. The structure of the device is P+—P2—P1—n1—n2—n+reverse biased to avalanche breakdown. P1—n1regions give the avalanche zone and P2 and n2 regions, the drift zones. Three structures have been considered, namely GaAs—Ge—GaAs, GaAs—Ge—Ge and Ge—Ge—GaAs. The first structure has two heterojunctions (i.e. P2—P1 and n1—n2 and second and third have one heterojunction (P1—P2 in second and n1—n2 in third). P1—n1, junction is of Ge in all the three structures.Plots of power and efficiency for these structures as a function of biasing-current density and impurity concentration reveal that in general, DDR H.J. Impatt diodes give more power and efficiency than the conventional GaAs DDR Impatts. GaAs/Ge/GaAs combination is found to be the best structure both in power and efficiency. The increase in efficiency is of the or...