InAlN‐barrier HFETs with GaN and InGaN channels

Abstract

Advantages and drawbacks of InN‐containing GaN‐based heterostructure field‐effect transistors (HFETs) are reviewed. The main attention is paid to fundamental processes and experimental observations associated with hot‐electron transport in two‐dimensional electron gas (2DEG) channels subjected to high electric fields. Complementary information is obtained from fluctuations. When interface roughness and alloy scattering are minimized, an important transport limitation originates from additional scattering of hot electrons by non‐equilibrium longitudinal optical (LO) phonons (hot phonons) governed by the hot‐phonon temperature and the hot‐phonon decay into acoustic phonons. The ultrafast decay is observed for high supplied power where the hot‐phonon lifetime of ∼60 fs is found. The optimal 2DEG density for the fastest decay of hot phonons is estimated and associated with LO‐phonon–plasmon resonance. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Temperature dependence of Mg-H local vibrational modes in heavily doped InN:Mg

“…GaN-based heterostructure field effect transistors (HFET) with InN-containing barrier/channel layers are the subject of intense current research. 1 The piezoelectric properties of group III nitrides also make these materials very attractive for surface acoustic wave (SAW) device applications. AlN is one of the most suitable materials for high-frequency filters, duplexers, and resonators because of its high SAW velocity and its insulating nature.…”

Limitation of Hot-Carrier Generated Heat Dissipation on the Frequency of Operation and Reliability of Novel Nitride-Based High-Speed HFETs

“…Fluctuationbased technique [16] was developed and implemented after careful analysis of different sources of hot-electron fluctuations in voltage-biased 2DEG channels at microwave frequencies [18,19]. The results on hot-phonon lifetime are available for nitride-based 2DEG channels [6,11,16,[20][21][22][23], arsenide-based 2DEG channels [24], SiO 2 /Si/SiO 2 channels [25], and SiC [26]. For recent reviews see [10][11][12][27][28][29].…”

“…A more sophisticated way for estimating the hot-phonon lifetime is based on estimation of equivalent hot-phonon temperature [20,23,28]. When the electron-LO-phonon interaction is the dominant electron energy dissipation mechanism, the hot-electron energy dissipation rate, or the dissipated power, is determined by the temperatures of hot electrons and hot phonons, T e and T LO .…”

“…(6) becomes of special importance when the lifetime depends on supplied power. The corresponding experimental data [6,10,11,23,28] for GaN 2DEG channels will be discussed later. Dependence of hot-phonon mode occupancy on supplied electric power for 2DEG channels: AlGaN/AlN/GaN (squares, after [20]) and InAlN/AlN/GaN (stars [11]).…”

“…We measure dependence of hot-phonon lifetime on electron density and supplied electric power [6,[10][11][12] beyond the ranges investigated by other techniques. Nominally undoped InAlN/AlN/GaN gateless structures and HFETs for this project were grown on c-plane semiinsulating GaN:Fe substrates (with a bulk resistivity of ~10 9 -cm) in a low-pressure customdesigned organo-metallic vapor phase epitaxy (OMVPE) system at Virginia Commonwealth University (Richmond, VA) [6][7][8]23]. The growth was initiated with a 250 nm AlN nucleation layer, and followed with a 2-4 m thick undoped GaN layer, a 1-nm-thick undoped AlN spacer layer, and a 18-nm-thick undoped InAlN barrier layer, and finally a ~2-nm-thick GaN cap layer.…”