Study Of Analytical Model Of Transport Properties And Applications In Wurtzite GaN And AlGaN Bulk Materials

Microwave power devices with conventional semiconductors have approachedtheir performance limits. To meet the future need in wireless communications, researcheffort has been directed to wide bandgap semiconductors such as GaN and SiC. GaNbased Gunn diodes are regarded as the promising microwave power devices above300GHz and even terahertz frequency range. However, some of the electrical propertiesin GaN based materials (including GaN, AlN, InN and their alloys ), for exampletransport properties, are not still acknowledged and understood completely. Previoustransport models also have bad defects. Pepole are just beginning to study the fators andlaws affecting performances of GaN based Gunn diodesand, and there is a lack ofunderstanding for them. All of these limit the steps of the design and applications.In the dissertation, the transport properties in wurtzite GaN and AlGaN bulkmaterials, and the factors and laws affecting the perfornances of GaN based Gunndiodes were studied. The major achievements are listed.Ⅰ.An analytical model of high-field transport properties in GaN and AlGaN for allkinds of Al compositions was proposed. The model can be applied into commercialsimulator SILVACO Simulator. For emphasis, the model remedied the defects ofprevious models in description of electron concentration dependence and temperaturedependence.II. For the first time, we proposed the random alloy potential dependence model ofhigh-field mobility, and introduced it into our model of transport properties. The modelcan give a more flexible and reasonable description of the random alloy potentialdependence of high-field mobility.III. Above model was applied in simulations of GaN based Gunn diode operatingin terahertz frequency range. The effects of temperature and random alloy potential onthe DC/RF conversion efficiency and frequency were revealed, and the optimal diodestructure was determined.