Study Of Microwave Power Devices

Since 90's of last century, the rapidly developing Information Technology (IT) has improved our life dramatically. As the foundation of the IT, Integrated Circuits (IC) has been paid attention more and more as well as communication technology, the key technology of ITs. On behalf of Communication technology, 3G (3rd Generation mobile communication) has met our increasing communication service qualities and then required ICs, especially power devices to have more progress than ever. How to improve the power devices applied in base-station of 3G is a great thesis confronted by us.SiC is the preferred material to fabricate high frequency and high power devices since it's excellent material characteristics. This paper makes a full research on frequency and power performances of MESFET of 4H-SiC, the material with the most performances in SiC materials as a whole. By theory analyzing and simulating using MEDICI, we have got a series of curves of device frequency and power performances versus it's geometry and physical parameters. We also designed the device structures with which the devices have 18.62 GHz ?T and 25.41 W/mm Pmax. These curves may provide references and guidelines for the researcher and developer to design high frequency and high power 4H-SiC MESFET for more optimizing performances based on the process themselves.On the other hand, the Si material, since it's mature process, the intergration to existing Si IC, and a series of advantages of Si MOSFETs compared with Si bipolar devices and excellent frequency linearity of Si LDMOS, all make microwave Si LDMOS the preferred device of microwave power devices. This paper introduces the concept of Composite Buffer (CB) originally applied in vertical devices into lateral RF LDMOS. By theory analyzing and simulation, compared with old RF RESURF LDMOS, we found that the new RF RESURF with embedded CB-layer exhibits a reduced on-resistance (about 28%) whereas there are nearly no breakdown and frequency performance degradations. In a word, SiC MESFET (even SiC MOSFET when the material characteristics mature) is the perfect microwave high temprature and high power devices. At present, however, since the immaturity of material and process of SiC, new structure especially the embedded CB-layer Si RF LDMOS devices are still the commercially practical microwave power devices.