Fabrication and characterisation of AlGaAs/InGaAs/GaAs pseudomorphic HEMT with in-situ epitaxial aluminium grown by MBE

The fabrication and characterisation of AlGaAs/InGaAs/GaAs pseudomorphic HEMT (P-HEMT) with an in-situ deposited epitaxial aluminium gate by MBE is reported. A simpler technique of fabricating a HEMT without the inherent problem associated with gate recess is described. Its advantages over conventional method of fabricating HEMTs are also shown. The near ideal epitaxial-Al/AlGaAs Schottky barrier contact is exploited in this work, resulting in excellent I-V and thermal treatment characteristics. This epitaxial Al diode has a better ideality factor, higher barrier height and higher breakdown voltage but higher series resistance than that of an Au diode