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

Van Zyl, Robert Ryk (2006-12)

Dissertation (PhD) -- University of Stellenbosch, 2006.

Thesis

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

AFRIKAANSE OPSOMMING: Die hoofnavorsingsdoel is die optimering van die uittree-drywing van GaAs Gunn diodes in die mm-golfspektrum. Die optimering van Gunn diodes by 94GHz word spesifiek ondersoek weens die relevansie tot huidige voertuig en militere presisie radartoepassings. 'n Nuwe multi-domein Gunn diode met meervoudige warm-elektron injektors word voorgestel en geevalueer. Hierdie konsep is suksesvol op 'n dubbeldomein diode toegepas. Verdere optimeringsopsies is ook geYnkorporeer. Dit sluit in kerf ("notch") dotering en die gradering van die doteringsprofiel in die aktiewe gebied. Uittree-drywing van ongeveer 160m W teen 2% effektiwiteit kan van hierdie diodes verwag word. Dit is aansienlik beter as huidige gespesialiseerde GaAs Gunn diodes wat in die omgewing van 90m W by 94GHz realiseer. ; Alhoewel dit nie pertinent ondersoek is nie, behoort die geoptimeerde diode dieselfde voordelige kenmerke te vertoon as die enkeldomein eweknie. Dit sluit in minder sensitiwiteit tot temperatuur- en voorspanningsveranderinge en verbeterde aanskakel-en geraaskarakteristieke. Die ontwerp is geoptimeer met 'n nuwe parallel-geYmplimenteerde Monte Carlo partikel simulasietegniek. 'n Groep persoonlike rekenaars, wat deur 'n hoe-spoed giga-bit netwerk verbind word, is opgerig. Hierdie implementering gee 'n koste-doeltreffende superrekenaar. Die simulasiemodel is noukeurig getoets teen praktiese eksperimente. Temperatuur-effekte is as integrale deel van die Monte Carlo model geYnkorporeer. Temperatuurprofiele word met hoe rooster-resolusie regdeur die diode bepaal en nie as konstant aanvaar nie. Dit stel ons in staat om die invloed van gegradeerde doteringsprofiele in die aktiewe gebiede op die werkverrigting van die diode te bepaal. Dit gee ook 'n meer realistiese model van hoe-temperatuur Gunn diodes.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/50663
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