ABSTRACT
Due to their attractive properties, group-III Nitrides (AlN, GaN and InN) and their ternary/quaternary compound based materials are increasingly getting a lot of an attention for applications in both optoelectronics and electronics. Due to the wide spectrum of energy bandgap (0.7 eV for InN to 6.2 eV for AlN) these materials find applications from infra red to ultra violet optoelectronics. GaN-based LEDs have already brought a revolution in the solid-state lighting industry. III-nitrides are also attractive for electronic applications for having properties like wide bandgap, very high electron density at the heterointerface due to polarization, high electron mobility, high critical electric field and high saturation velocity. These properties qualify GaN-based HEMTs for applications in high power, high frequency and high temperature applications. Among different GaN-based HEMTs, AlGaN/GaN technology is the most mature and has already been commercialized. This chapter discusses the fabrication process of GaN-based HEMTs primarily emphasizing on AlGaN/GaN HEMTs. Process steps like dry etching of GaN-based materials, ohmic contact metallization, lithography, passivation and some other special techniques like (fluorinated gate HEMT, p-GaN gated HEMT, field plate, MIS-HEMT technology) are separately discussed in detail. Challenges associated with AlGaN/GaN HEMT technology are also discussed.
