Microwave Power Semiconductor Devices. I Critical Review

Abstract

This chapter focuses on the two-terminal devices, that is, bulk and junction diodes of the microwave power semiconductor devices. The two-terminal devices are mostly used to make oscillators. However, with certain provisions, they may also be used for amplifiers or switching devices, although the circuits involved may increase in complexity. Most early Gunn diodes were realized from an n + nn sandwich system on bulk material. However, heat evacuation from the bulk appeared difficult. Avalanche junction diodes appear as a direct consequence of the extension to semiconductor materials of spark triggering theory in gases by electron avalanche formation. The basic principle of Barrier Injection Transit Time (BARITT) diodes is space-charge limited emission in semiconductors and negative conductance arising from transit time of injected carriers. As a frequency multiplier, the varactor diode is a complementary device designed to improve the frequency performance of a main device, such as a transistor or a negative-resistance diode. The application of such varactors has been, therefore, mainly developed as an extension of the transistor or sometimes diode, amplifier or oscillator.