The optimisation of mm-Wave GaAs Gunn diodes using a parallel implementation of the Monte Carlo particle simulation technique

[摘要] ENGLISH ABSTRACT: The principal research objective is the optimisation of the output power of GaAs Gunn diodesin the mm-wave spectrum. Specifically, the optimisation of Gunn diodes operating at 94GHzis investigated due to its relevance to current automotive and military precision radarapplications.A novel multi-domain Gunn diode with multiple hot-electron launchers is proposed andevaluated. This concept has been successfully applied to a double-domain Gunn diode. Furtheravenues of optimisation that have been incorporated into the design are notch doping and gradingof the active layer doping profile. Output power in the region of 160m W at 2% efficiency canbe expected from these diodes. This is far superior to current state-of-the-art GaAs Gunn diodeswhich are capable of around 90m W at 94GHz.Although it has not been investigated, the optimised diode should benefit from the sameadvantages of a single domain hot-electron launcher diode. These advantages are reducedsensitivity to temperature and bias variations, improved tum-on characteristics and noiseperformance.The design has been optimised using a novel parallel implementation of the Monte Carlo particlesimulation technique. A cluster of personal computers, linked via a dedicated high-speed gigabitnetwork, has been established. This renders a cost-effective super computer. The simulationmodel has been verified rigorously by comparing simulation results with real-life scenarios.Thermal effects are incorporated into the overall Monte Carlo model. Temperature is determinedwith fine grid-resolution throughout the device and not assumed constant. This enables us toinvestigate the influence of graded doping profiles on device performance in. more detail, andrenders a more realistic model of high temperature Gunn diodes.

[发布机构] Stellenbosch University