Browsing by Author "Kaya, İ. İ."
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Item Open Access Frequency-dependent piezoresistive effect in top-down fabricated gold nanoresistors(American Chemical Society, 2021-08-11) Arı, A. B.; Karakan, M. Ç.; Yanık, C.; Kaya, İ. İ.; Hanay, Mehmet Selim; Svitelskiy, O.; González, M.; Seren, H.; Ekinci, K. L.Piezoresistive strain gauges allow for electronic readout of mechanical deformations with high fidelity. As piezoresistive strain gauges are aggressively being scaled down for applications in nanotechnology, it has become critical to investigate their physical attributes at different limits. Here, we describe an experimental approach for studying the piezoresistive gauge factor of a gold thin-film nanoresistor as a function of frequency. The nanoresistor is fabricated lithographically near the anchor of a nanomechanical doubly clamped beam resonator. As the resonator is driven to resonance in one of its normal modes, the nanoresistor is exposed to frequency-dependent strains of ε ≲ 10–5 in the 4–36 MHz range. We calibrate the strain using optical interferometry and measure the resistance changes using a radio frequency mix-down technique. The piezoresistive gauge factor γ of our lithographic gold nanoresistors is γ ≈ 3.6 at 4 MHz, in agreement with comparable macroscopic thin metal film resistors in previous works. However, our γ values increase monotonically with frequency and reach γ ≈ 15 at 36 MHz. We discuss possible physics that may give rise to this unexpected frequency dependence.Item Open Access Optimization of piezoresistive motion detection for ambient NEMS applications(Institute of Electrical and Electronics Engineers, 2020) Ti, C.; Arı, A.; Orhan, E.; Gonzalez, M.; Yanık, C.; Kaya, İ. İ.; Hanay, Mehmet Selim; Ekinci, K. L.Electrical readout of nanomechanical motion in ambient pressure and temperature imposes an important challenge for emerging applications of nanoelectromechanical systems (NEMS). Here, we optimize a metallic piezoresistive motion transducer for NEMS resonators in air. The nanomechanical motion of the NEMS resonator serves as a signal down-mixer and enables the detection of the motional signal by a low-frequency circuit. A balanced circuit in the detection loop reduces some of the unwanted background and allows for detection without significant losses. We explore the detection parameter space and use an optimized parameter set to detect the fundamental, second and third harmonic resonances of a NEMS doubly-clamped beam resonator. Our simple circuit model agrees with experimental observations and points the way for further optimization.