Performance of double heterostructure unipolar transistors in high frequency power applications

Abstract

The fabrication of a vertical hot electron transistor incorporating a two-dimensional electron gas (2DEG) is demonstrated in the GaAs AlGaAs materials system. The difficulties caused by the need to form selective ohmic contacts to the different conducting layers have been overcome using a combination of in situ focussed ion beam (FIB) isolation and molecular beam epitaxial (MBE) regrowth. This has allowed a high yield of working devices to be achieved with h fe = 4 at 77 K. The high frequency ( f max ≈ 100 GHz) current drive capability of this device will be discussed.