17:45 〜 18:00
▲ [13p-N101-18] Self-temperature-compensated GaN MEMS resonator through strain engineering
キーワード：GaN
The micro-electromechanical or nano-electromechanical systems (MEMS/NEMS) for reference oscillators toward the millimetre-wave 5G systems represent a privileged way to achieve high resonance frequencies with less phase noise and high temperature stability. Unfortunately, due to the negative temperature coefficient of the elasticity, the Si-based MEMS resonator normally exhibits a large negative temperature coefficient of frequency (TCF) around -30 ppm/K. The temperature compensation techniques have been proposed, for example, geometry modification, impurities doping, and multilayer structures, however, the quality (Q) factors of the systems were greatly degraded.
III-V nitride semiconductors are the excellent candidates for high-frequency electronics in 5G era. The integration of III-V nitrides MEMS with electronics are thus promising and timely important for IoT sensors and communications. The great progress of the high-quality GaN on Si substrates with large scales further makes the possibility of the GaN-based MEMS/NEMS integrated with the semiconductor technology.
In this work, we demonstrate a marked improvement of the TCF of several ppm/K for the GaN MEMS resonators without losing the Qfactors up to 600 K by using elastic strain engineering for the self-temperature compensation. The double-clamped GaN resonators were fabricated from GaN on Si substrate. To introduce the stress in the epitaxial GaN layer, the GaN layer was directly grown on the AlN/Si (111) buffer. A high Q factor more than 105 for the MEMS resonator was achieved. Both ultra-low TCF and high Q factors are tailored by using stress induced bulking resonance modes. Different from the conventional flexural modes, the internal thermal stress improves the TCF of the GaN resonator by over 10 times to be as low as ~ppm/K even at 400K, without losing the high Q factor even up to 600 K.
III-V nitride semiconductors are the excellent candidates for high-frequency electronics in 5G era. The integration of III-V nitrides MEMS with electronics are thus promising and timely important for IoT sensors and communications. The great progress of the high-quality GaN on Si substrates with large scales further makes the possibility of the GaN-based MEMS/NEMS integrated with the semiconductor technology.
In this work, we demonstrate a marked improvement of the TCF of several ppm/K for the GaN MEMS resonators without losing the Qfactors up to 600 K by using elastic strain engineering for the self-temperature compensation. The double-clamped GaN resonators were fabricated from GaN on Si substrate. To introduce the stress in the epitaxial GaN layer, the GaN layer was directly grown on the AlN/Si (111) buffer. A high Q factor more than 105 for the MEMS resonator was achieved. Both ultra-low TCF and high Q factors are tailored by using stress induced bulking resonance modes. Different from the conventional flexural modes, the internal thermal stress improves the TCF of the GaN resonator by over 10 times to be as low as ~ppm/K even at 400K, without losing the high Q factor even up to 600 K.