Comparison of Different Cooling Schemes for AlGaN/GaN High-Electron Mobility Transistors.

Abstract

Cooling is important for AlGaN/GaN high-electron mobility transistors (HEMTs) performance. In this paper, the advantages and disadvantages of the cooling performance of three cooling schemes: remote cooling (R-cool), near-chip cooling (NC-cool), and chip-embedded cooling (CE-cool) are compared. The influences of distinct geometric parameters and operating conditions on thermal resistance are investigated. The results show that the thermal resistances of NC-cool and CE-cool are almost the same as each other. Decreasing microchannel base thickness (<i>h_b</i>) significantly increases the thermal resistance of CE-cool, and when its thickness is less than a critical value, NC-cool exhibits superior cooling performance than CE-cool. The critical thickness increases when decreasing the heat source pitch (<i>P_h</i>) and the convective heat transfer coefficient (<i>h_conv</i>) or increasing the thermal conductivity of the substrate (<i>λ_sub</i>). Moreover, increasing <i>P_h</i> or <i>λ_sub</i> significantly improves the thermal resistance of three cooling schemes. Increasing <i>h_conv</i> significantly decreases the thermal resistances of NC-cool and CE-cool while hardly affecting the thermal resistance of R-cool. The influence of the boundary thermal resistance (<i>TBR</i>) on the thermal resistance significantly increases at higher <i>λ_sub</i> and larger <i>h_conv</i>.