applications (eg for algaas on gaas) are similar to those of mesfets – microwave and millimeter wave communications, imaging, radar, and radio astronomy – any application where high gain and low noise at high frequencies are required. hemts have shown current gain to frequencies greater than 600 ghz and power gain to frequencies greater than 1 thz. (heterojunction bipolar transistors were demonstrated at current gain frequencies over 600 ghz in april 2005.) numerous companies worldwide develop and manufacture hemt-based devices. these can be discrete transistors but are more usually in the form of a 'monolithic microwave integrated circuit' (mmic).