Design, Fabrication, Packaging, and Characterization of Nano Inertial and FET Sensors

Abstract

Miniaturization is necessary and unavoidable for the advancement of sensor technology. This thesis explores the effect of miniaturization on performance and proposes solutions to addressed challenges through the development of a novel packaging solution and engineering device interfaces.

First, a theoretical model is developed to understand the impact of miniaturization on sensor properties such as sensitivity and signal-to-noise ratio for nano and micro electro mechanical systems-based (N/MEMS-based) gas sensing applications. Then, these theoretical predictions are experimentally verified through the experimental comparison of NEMS and MEMS-based humidity sensors. The experiments confirm that miniaturization enhances the sensitivity of inertial gas sensors. However, it also introduces challenges such as lower signal-to-noise ratio (SNR) due to attenuated output signals that are more susceptible to noise, thereby motivating the development of improved packaging and interface solutions.

To minimize the noise sources, a novel packaging technique, called built-in packaging, is proposed and performance of MEMS resonators and metal-insulator-metal (MIM) diodes are compared with the conventional techniques such as wire bonding and probing. Experimental results show that built-in packaging methods enhance output signal levels by 12\% while preserving overall performance.

Finally, to implement novel materials into sensing technologies, interface engineering is studied for development of colloidal quantum dot based field effect transistors (CQD-based FETs). These devices can quantify the electrical properties of novel CQDs and highlights the importance of interface engineering. The quantified results accelerates the development of improved CQDs, leading to better photodetector performance in infrared (IR) detection.

Overall, this thesis presents a detailed analysis of the trade-offs in sensor miniaturization and provides critical insight for the advancement of compact and high-performance sensors.