Self-heating study of an AlGaN/GaN-based heterostructure field-effect

We report micro-Raman studies of self-heating in an AlGaN/GaN heterostructure field-effect transistor using below svisible 488.0 nmd and near sUV 363.8 nmd GaN band-gap excitation. The shallow penetration depth of the UV light allows us to measure temperature rise sDTd in the two-dimensional electron gas s2DEGd region of the device between drain and source. Visible light gives the average DT in the GaN layer, and that of the SiC substrate, at the same lateral position. Combined, we depth profile the self-heating. Measured DT in the 2DEG is consistently over twice the average GaN-layer value. Electrical and thermal transport properties are simulated. We identify a hotspot, located at the gate edge in the 2DEG, as the prevailing factor in the self-heating