Probing channel temperature profiles in AlxGa1−xN/GaN high electron mobility transistors on 200 mm diameter Si(111) by optical spectroscopy

• Published in: Applied physics letters Vol. 105; no. 7
• Main Authors: Bera, L K, Liu, Y, Bera, M K, Singh, S P, Dolmanan, S B, Tan, H R, Bhat, T N, Chor, E F, Tripathy, S
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 18-08-2014
• Subjects: Applied physics; Gallium nitrides; High electron mobility transistors; Photoluminescence; Semiconductor devices; Silicon substrates; Temperature profiles; Thermal resistance; Transistors
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4893603

Using micro-Raman and photoluminescence (PL) techniques, the channel temperature profile is probed in AlxGa1-xN/GaN high electron mobility transistors (HEMTs) fabricated on a 200 mm diameter Si(111) substrate. In particular, RuOx-based gate is used due to the semitransparent nature to the optical excitation wavelengths, thus allowing much accurate thermal investigations underneath the gate. To determine the channel temperature profile in devices subjected to different electrical bias voltages, the GaN band-edge PL peak shift calibration with respect to temperature is used. PL analyses show a maximum channel temperature up to 435 K underneath the gate edge between gate and drain, where the estimated thermal resistance in such a HEMT structure is about 13.7 KmmW−1 at a power dissipation of ∼10 W/mm. The temperature profiles from micro-Raman measurements are also addressed from the E2-high optical phonon peak shift of GaN, and this method also probes the temperature-induced peak shifts of optical phonon from Si thus showing the nature of thermal characteristics at the AlN/Si substrate interface.