Thermometry of AlGaN/GaN HEMTs Using Multispectral Raman Features

• Published in: IEEE transactions on electron devices Vol. 60; no. 6; pp. 1898 - 1904
• Main Authors: Sukwon Choi, Heller, E. R., Dorsey, D., Vetury, R., Graham, S.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-06-2013; Institute of Electrical and Electronics Engineers
• Subjects: Aluminum gallium nitride; Applied sciences; Electronics; Exact sciences and technology; Gallium nitride; HEMTs; Imaging devices; Microelectronic fabrication (materials and surfaces technology); MODFETs; Phonons; Raman scattering; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Stress; Temperature measurement; Transistors; Ternary compound; Thermal stress; Binary compound; Thermoelastic stress; State of the art; Aluminium nitride; Gallium nitride; III-V compound; Temperature measurement; High electron mobility transistor; Frequency shift; Microelectronic fabrication; Raman scattering; Line width; HEMTs; Raman spectrometry; Thermal imaging; Monitoring; Wafer; Thermography
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2013.2255102

In this paper, we utilize micro-Raman spectroscopy to measure temperature and stress in state-of-the-art AlGaN/GaN HEMTs. A rigorous discussion on the physical accuracy, precision, and precautions for diverse Raman thermometry methods is developed. Thermometry techniques utilizing shifts in a single Raman Stokes peak position underpredict the channel temperature due to induction of operational thermoelastic stress in operating devices. Utilizing the change in phonon linewidth by employing a proper reference condition gives true temperature results. Making use of frequency shifts in both the E 2 (high) and A 1 (LO) phonon modes offers accurate and time-efficient means to determine the state of temperature and thermal stress in operating AlGaN/GaN HEMTs presuming that linear relations between phonon frequencies and temperature/stress are well determined. Useful applications of this method such as monitoring stress in GaN wafers between fabrication steps and Raman thermography on AlGaN/GaN HEMTs are demonstrated.