Ultrafast decay of non‐equilibrium (hot) phonons in GaN‐based 2DEG channels

Abstract

Fast and ultrafast decay of non‐equilibrium longitudinal optical phonons (hot phonons) is discussed on examples of two‐dimensional electron gas (2DEG) channels confined in nominally‐undoped nitride and selectivelydoped arsenide heterostructures subjected to pulsed dc electric power. At a low–moderate power, a nonmonotonous dependence of the hot‐phonon lifetime on the 2DEG density is found. The fastest decay takes place at ∼2.5 × 1012 cm–2 in GaInAs 2DEG channel and at ∼7 × 1012 cm–2 in GaN 2DEG channel. The result is discussed in terms of plasmon–LO‐phonon resonance. The hot‐phonon lifetime decreases when the supplied power is increased if the 2DEG density exceeds the resonance density. The shortest hot‐phonon lifetime of 60 fs is obtained at/above 50 nW/electron for the lattice‐matched AlInN/AlN/GaN 2DEG channel (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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

“…According to Monte Carlo simulation, the noise temperature T n is close to the hot-electron temperature T e [11,32] (Fig. 5, circles and line).…”

“…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].…”

“…The dependence can be obtained from the experimental dependence of the hot-phonon temperature on the supplied power for GaN 2DEG channels [11,20]. The effective dynamic hot-phonon lifetime is introduced as follows [11]:…”

“…(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]).…”

“…The conversion of the LO-mode heat into the LA-mode heat can be treated in terms of LO-phonon lifetime, associated with the decay of the LO phonons into other modes, for example, transverse optical (TO) and (mobile) LA modes through the route LO TO+LA proposed for GaN some time ago [9]. In nitride 2DEG channels, the exact route of LO-phonon decay is not clearly understood but there is compelling experimental [6,[10][11][12] and theoretical [13] evidence that plasmon-assisted process tends to dominate.…”