Nematic Liquid Crystal Composite Materials for DC and RF Switching

Project by Mohiuddin Munna Liquid Crystals (LC) are widely used in displays, electro-optic modulators, and optical switches. In these types of devices, an electric field is applied which modulates the optical properties of the LC material. It is attractive for its low power consumptions. Opto-electronic devices and switches made from LC materials consume comparatively less power than […]

MEMS based Gas Sensing

Project by Turja Nandy

In this project, we will introduce MEMS membrane-based photo-acoustic (PA) detection system for a hazardous gas sensing application with high accuracy and low cost. We will use thin and deformable micro-machined SOI membrane to detect the acoustic vibration created via light-gas interaction inside the PA chamber. In this work, firstly, we will analyze the theory behind photo-acoustic phenomena and pressure change inside gas chambers for proper modeling of a MEMS membrane. Then, we will fabricate the MEMS membrane and prepare the whole optical experimental set-up with a LED-based infrared (IR) light source and detector according to the absorption spectra of target gases. Finally, we will detect the membrane deflection caused by acoustic vibrations and pressure change through a white light interferometer. These deflection values will give the sensitivity towards the particular gas.

 

Novel Test Fixture for Studying Microcontact Reliability and Performance

Project by Protap Mahanta

Microelectromechanical systems (MEMS) technology is widely used in applications ranging from sensing to switching technology due to its low cost, low power consumption, and small geometries. Microswitches are an example of a MEMS technology that shows promising performances in direct current (DC) and radio frequency (RF) applications. However, reliability is of great concern for them to be ubiquitously used by the industry where the lifetime requirement is typically 1-10 billion cycles depending on the specific application. Microcontact surface tribology plays a crucial role in determining reliability and performance. A test fixture facilitates to study contact force, contact resistance, adhesion, and contamination associated with the microcontact. Currently, we are developing an improved microcontact support structure which enables a simple, quick, and easy post-mortem contact surface analysis. In addition, engineered micro-electrical contacts will be fabricated and tested using our novel test fixture for acquiring significant data to design a robust and reliable MEMS switch for future DC and RF applications.

Figure 1. Schematic representation of the microcontact test fixture assembly.

Thin Films

Gallium nitride (GaN), a wide bandgap semiconductor, has few superior material properties such as: a large electric breakdown field, high electron velocity, and mobility, which makes it a potential candidate for next generation electrical and optoelectrical applications. At present, most of the GaN growth is done on relatively expensive substrates i.e. sapphire and SiC by using high-temperature deposition methods (MBE, MOCVD etc). On the other hand, Silicon substrates are cheap, available in large diameters and have well characterized electrical and thermal properties. Despite all these advantages, GaN on Si is not studied much because of the cracking problem in GaN films which becomes worse at a higher temperature. Therefore, our focus is to grow the good quality and less stressed GaN films on Si, using the low-temperature atomic layer deposition (ALD) method. In the future, our plan is to design and fabricate GaN/Si devices and study their reliability, performance for industrial applications.