Self-heating study of an AlGaN/GaN-based heterostructure field-effect transistor using ultraviolet micro-Raman scattering

We report micro-Raman studies of self-heating in an AlGaN/GaN heterostructure field-effect transistor using below (visible 488.0 nm) and near (UV 363.8 nm) GaN band-gap excitation. The shallow penetration depth of the UV light allows us to measure temperature rise (AT) in the two-dimensional electron gas (2DEG) region of the device between drain and source. Visible light gives the average Delta T in the GaN layer, and that of the SiC substrate, at the same lateral position. C Combined, we depth profile the self-heating. Measured Delta T, in the 2DEG is consistently over twice the average GaN-layer value. Electrical and thermal transport properties are simulated. We identify a hot spot, located at the gate edge in the 2DEG, as the prevailing factor in the self-heating. (c) 2005 American Institute of Physics.