Surface Acoustic Wave Devices On Bulk Zno Crystals At Low Temperature

Surface acoustic wave (SAW) devices based on thin films of ZnO are a well established technology. However, SAW devices on bulk ZnO crystals are not practical at room temperature due to the significant damping caused by finite electrical conductivity of the crystal. Here, by operating at low temperatures, we demonstrate effective SAW devices on the (0001) surface of bulk ZnO crystals, including a delay line operating at SAW wavelengths of lambda = 4 and 6 mu m and a one-port resonator at a wavelength of lambda = 1.6 lm. We find that the SAW velocity is temperature dependent, reaching v similar or equal to 2.68 km/s at 10 mK. Our resonator reaches a maximum quality factor of Q(i) similar or equal to 1.5 x 10(5), demonstrating that bulk ZnO is highly viable for low temperature SAW applications. The performance of the devices is strongly correlated with the bulk conductivity, which quenches SAW transmission above 200 K. (C) 2015 AIP Publishing LLC.