Transient Thermal Management of a β-Ga₂O₃ MOSFET Using a Double-Side Diamond Cooling Approach

• Published in: IEEE transactions on electron devices Vol. 70; no. 4; pp. 1628 - 1635
• Main Authors: Kim, Samuel H., Shoemaker, Daniel, Green, Andrew J., Chabak, Kelson D., Liddy, Kyle J., Graham, Samuel, Choi, Sukwon
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-04-2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Computer architecture; Cooling; Diamonds; Diffusivity; Direct current; Electric field strength; Gallium nitrides; Gallium oxide (β-Ga₂O₃); Gallium oxides; Heat conductivity; Heat transfer; Logic gates; MOSFET; Overheating; Performance degradation; Raman thermometry; Side cooling; Silicon carbide; Substrates; Switching; Thermal conductivity; Thermal diffusivity; Thermal management; Time constant; Transient analysis; Transistors; ultrawide bandgap (UWBG) semiconductor devices
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2023.3244134

<inline-formula> <tex-math notation="LaTeX">\beta </tex-math></inline-formula>-phase gallium oxide (<inline-formula> <tex-math notation="LaTeX">\beta </tex-math></inline-formula>-Ga2O3) has drawn significant attention due to its large critical electric field strength and the availability of low-cost high-quality melt-grown substrates. Both aspects are advantages over gallium nitride (GaN) and silicon carbide (SiC) based power switching devices. However, because of the poor thermal conductivity of <inline-formula> <tex-math notation="LaTeX">\beta </tex-math></inline-formula>-Ga2O3, device-level thermal management is critical to avoid performance degradation and component failure due to overheating. In addition, for high-frequency operation, the low thermal diffusivity of <inline-formula> <tex-math notation="LaTeX">\beta </tex-math></inline-formula>-Ga2O3 results in a long thermal time constant, which hinders the use of previously developed thermal solutions for devices based on relatively high thermal conductivity materials (e.g., GaN transistors). This work investigates a double-side diamond-cooled <inline-formula> <tex-math notation="LaTeX">\beta </tex-math></inline-formula>-Ga2O3 device architecture and provides guidelines to maximize the device's thermal performance under both direct current (dc) and high-frequency switching operation. Under high-frequency operation, the use of a <inline-formula> <tex-math notation="LaTeX">\beta </tex-math></inline-formula>-Ga2O3 composite substrate (bottom-side cooling) must be augmented by a diamond passivation overlayer (top-side cooling) because of the low thermal diffusivity of <inline-formula> <tex-math notation="LaTeX">\beta </tex-math></inline-formula>-Ga2O3.