Hot-Electron Transport and Noise in GaN Two-Dimensional Channels for HEMTs


IEICE TRANSACTIONS on Electronics   Vol.E89-C   No.7   pp.913-920
Publication Date: 2006/07/01
Online ISSN: 1745-1353
Print ISSN: 0916-8516
Type of Manuscript: INVITED PAPER (Special Section on Heterostructure Microelectronics with TWHM2005)
GaN,  AlGaN,  high-electron-mobility transistor (HEMT),  two-dimensional electron gas (2DEG),  microwave frequency,  

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Accumulation of non-equilibrium longitudinal optical (LO) phonons (termed hot phonons) is considered as a possible cause for limitation of frequency of operation of GaN-based high-electron-mobility transistors (HEMTs). The experimental data on noise temperature of hot electrons at a microwave frequency as a function of supplied electric power is used to extract information on hot phonons: the hot-phonon lifetime, the equivalent hot-phonon temperature, the effective occupancy of hot-phonon states involved into electron-LO-phonon interaction. The possible ways for controlling the hot-phonon effect on electron drift velocity through variation of electron density, channel composition, and hot-phonon lifetime are discussed. The expected dependence of hot-electron drift velocity on hot-phonon lifetime is confirmed experimentally. A self-consistent explanation of different frequency behaviour of InP-based and GaN-based HEMTs is obtained from a comparative study of hot-phonon effects.