Carbon nanotube as electrode in film bulk acoustic wave resonator for improved performance

Abstract

Electrode material is one of the important material in designing FBAR. Different electrode materials will have different characteristic and properties. The different in properties will also produce different performance such as the quality factor or electromechanical coupling coefficient (k2eff). Study has shown that carbon nanotube (CNT) has been used as electrode in the fabrication of FBAR. The result shows that CNT offers higher Q factor compare to metal electrode. Therefore, in this work it is focused to design the zinc oxide (ZnO) based on FBAR with carbon nanotube (CNT) and aluminium (Al) as electrode with frequencies range of 6 GHz to 8 GHz. Analysis shows that CNT has higher Q factor compared to Al where the highest Q factor of CNT recorded is 1543 while Al is 1268 at frequency of 8 GHz with thickness of 30 nm at resonance area of 50 μm × 50 μm. For FBAR operation at 6 GHz, CNT shows the highest Q factor of 1164 while Al is 876 at thickness of 30 nm at resonance area of 50 μm × 50 μm. CNT and Al at 7 GHz also show the highest Q factor at thickness of 30 nm with resonance area of 50 μm × 50 μm by 1341 and 993 respectively. On the other hand, in term of k2eff, Al has higher value of k2eff compare to CNT where for 6 GHz the highest value of Al recorded is 0.062 while CNT is 0.026 at thickness of 30 nm with resonance area of 50 μm × 50 μm. For 7 GHz the highest k2eff of Al achieved is 0.067 while CNT is 0.042 at thickness of 30 nm. For 8 GHz, the highest k2eff of Al achieved is 0.073 while CNT is 0.025 at thickness of 30 nm.