Gallium nitride based transistors

Abstract

An overview is presented of progress in GaN electronic devices along with recent results from work at UCSB. From 1995 to 2001, the power performance of AlGaN/GaN high electron mobility transistors (HEMT) improved from 1.1 to 11 W mm-1, respectively. The disadvantage of the low thermal conductivity of the sapphire substrate was mitigated by flip-chip bonding onto AlN substrates, yielding large periphery devices with an output power of 7.6 W. A variety of HEMT amplifier circuits have been demonstrated. The first AlGaN/GaN heterojunction bipolar transistor (HBT) was demonstrated in 1998, with a current gain of about 3. By developing the technique of emitter regrowth, a current gain of 10 was achieved in both GaN BJTs and AlGaN/GaN HBTs. A common emitter current gain cutoff frequency of 2 GHz was measured. Critical issues involved in the growth of high quality AlGaN/(AlN)/GaN heterostructures and GaN:Mg by metal-organic chemical vapour deposition (MOCVD) and molecular beam epitaxy (MBE) and the device fabrication are discussed.

Solid-State Lighting Based on Light Emitting Diode Technology

“…AlGaN/GaN heterostructures are also suitable for electronic devices such as high electron mobility transistors (HEMTs), which have applications in microwave and radio frequency power amplifiers used for communications technology [9]. Such a wide bandgap materials system also allows device operation at higher voltages and temperatures compared to conventional Si, GaAs or InP-based electronics [10].…”

Development of 2" AlN Substrates Using SiC Seeds

“…• high power/high frequency electronic devices capable of operating at high temperatures and in harsh environment (Bennett et al, 2004;Morkoc, 1998;Pearton et al, 2000;Shur, 1998;Skierbiszewski, 2005;Xing et al, 2001). …”

High field effects of GaN HEMTs.

“…High electron mobility transistors (HEMT's) fabricated from AlGaN/GaN heterostructures have shown great potential for microwave power devices [1,2,3,4]. In these heterostructures (and in the HEMTs made with these heterostructures), there is a difference in the polarization field between the top layer (AlGaN) and that in the bottom layer (GaN).…”