Concepts  3 HEMT basic

   3.4 HEMT operation


high electron mobility transistor (HEMT) is a kind of a field effect transistor where the current flow between two ohmic contacts, source and drain, is controlled by a third contact, the gate which may be a Schottky barrier contact in most cases.(1)  Usually a field effect transistors channel is formed by a doped region as is generally the case for well known metal oxid semiconductor field effect transistor - MOSFET. Instead of that, HEMT incorporates a junction between two different semiconductor materials (i.e. a heterojunction) as the channel. The current is controlled in a way, that the transistor channel is normally open without gate biased (Fig. 3.6) .

HEMT advantages:

  • High speed
  • High gain
  • Low noise
  • High power density

HEMT operation

Fig. 3.6 HEMT operation


(1) Helmut Brech, The Principles of a HEMT, [online] 1998, [cit. 2015-10-10]