Thermal Modeling of Extreme Heat Flux Microchannel Coolers for GaN-on-SiC Semiconductor Devices

Abstract

Gallium nitride (GaN) high-electron-mobility transistors (HEMTs) dissipate high power densities which generate hotspots and cause thermomechanical problems. Here, we propose and simulate GaN-based HEMT technologies that can remove power densities exceeding 30 kW/cm 2 at relatively low mass flow rate and pressure drop. Thermal performance of the microcooler module is investigated by modeling both single-and two-phase flow conditions. A reduced-order modeling approach, based on an extensive literature review, is used to predict the appropriate range of heat transfer coefficients associated with the flow regimes for the flow conditions. Finite element simulations are performed to investigate the temperature distribution from GaN to parallel microchannels of the microcooler. Single-and two-phase conjugate computational fluid dynamics (CFD) simulations provide a lower bound of the total flow resistance in the microcooler as well as overall thermal resistance from GaN HEMT to working fluid. A parametric study is performed to optimize the thermal performance of the microcooler. The modeling results provide detailed flow conditions for the microcooler in order to investigate the required range of heat transfer coefficients for removal of heat fluxes up to 30 kW/cm 2 and a junction temperature maintained below 250 C. The detailed modeling results include local temperature and velocity fields in the microcooler module, which can help in identifying the approximate locations of the maximum velocity and recirculation regions that are susceptible to dryout conditions.

Thermal Energy Processes in Direct Steam Generation Solar Systems: Boiling, Condensation and Energy Storage – A Review

“…Zhang et al (2016g) observed that at low inlet subcooling temperatures of 10 and 40 K, the heat transfer coefficient was significantly increased with a reduced pressure drop along the channel. Lee et al (2016) computed the heat transfer coefficient of GaN-on-SiC semiconductors devices for the various flow regimes. For the bubbly flow regime, an increase in mass flux suppressed nucleate boiling growth, which consequentially decreased the heat transfer coefficient.…”

“…They discovered that the pressure drop increased significantly with an increase in inlet velocity. Lee et al (2016) studied GaN-on-SiC semiconductor microchannel coolers devices with high heat flux, focusing on the heat transfer and flow phenomena. They compared the effect of tapered channel design (45 • tapered) with an un-tapered channel design at varying mass fluxes.…”

Advanced Characterization Techniques and Analysis of Thermal Properties of AlGaN/GaN Multifinger Power HEMTs on SiC Substrate Supported by Three-Dimensional Simulation

“…Recent progress in GaN-based high-electron mobility transistors (HEMTs) has confirmed them to be the main transistor technology for upcoming high-power devices at high-frequency operation because of their excellent electronic properties, especially high-electron saturation velocity, and high breakdown voltage [1][2][3][4][5][6]. Multifinger devices with a compact layout are required for high-power operation.…”

Thermal management of GaN HEMT devices using serpentine minichannel heat sinks

“…However, GaN HEMTs dissipate large heat fluxes which create hotspots that can cause significant degradation in performance [3] when maximum operating temperatures of ~250 o C are exceeded. To alleviate the problem of hotspots, silicon carbide (SiC) heat spreaders have been used due to their high thermal conductivity of 370 W/m.K at 20 o C [4]. However, since the thermal conductivity of SiC decreases significantly as temperature increases [5], the use of SiC alone is not practical for hot spot mitigation.…”

“…For example, Calame et al [10] used experiments and numerical simulations to study the dissipation of 4 kW/cm 2 over a 1.2 × 5 mm 2 active area of a GaN on SiC semiconductor using water-cooled microchannel coolers, while the experimental study of Lee et al [11] investigated how to dissipate a heat flux of 11.9 kW/cm 2 over eight heat sources of size 350 × 150 µm 2 on a 7 × 7 mm 2 silicon (Si) die with a maximum hotspot temperature of 175°C. Recently, Lee et al [12,13] used 3-D numerical simulations to analyse the thermal conditions when a total power of 92.4 W is applied to 40 multiple gates (a heat flux of 330 kW/cm 2 is applied to each gate) located on GaN HEMTs on a SiC-based microchannel heat sink using water and methanol as a coolants in single and two phase flow conditions. Other relevant studies have focused on the effect of using very high thermal conductivity substrates to enhance heat spreading for GaN and a number of these have analysed diamond heat spreaders [14 -16] since diamond's thermal conductivity is 2200 W/m.K -5.5 times greater than copper [17].…”