GAAS-MESFET AND RELATED PROCESSES

Since inception of GaAs MESFET in 1971, growth and processing technology of GaAs has matured to the extent that the analogue as well as digital IC production is persued at the industrial level. The ever increasing demand for higher frequency of operation, low noise figure and higher gain has led to newer device structures such as HEMT and HJBT based on GaAs and related compounds. Furthermore there exists exciting and proven capabilities in GaAs and related compounds to generate, detect and convert light into electrical signals. This has opened up vast field of opto-electronic devices and their integration with MESFET and other conventional devices. Basic building block of all these developmental activities still remains the GaAs MESFET, which have also been extensively used as low noise amplifiers, mixers, oscillators and high power amplifiers in descrete form. This paper reviews the design aspects, fabrication technology, d.c. and microwave characterization for both low noise and high power MESFET. Various technological advancements like via-hole for source grounding, air-bridge technology for low parasitic interconnects and polymide passivation, which have helped in further improvement in terms of higher frequency of operation, low noise and high power output are reviewed. Finally some representative results on the devices fabricated at CEERI are also presented. © 1990 The Indian Academy of Sciences.