Engineering Commons^™

An Ion Detection Scheme Employing Solid State Devices For Use In Portable Mass Spectrometers, Sanjiv Nath Pant

Theses and Dissertations

This thesis presents a solid state approach to the ion detection system used in the back-end of modern mass spectrometers. Although various techniques already exist to detect ions – even with the sensitivity of a single particle, the existing techniques require high voltage or lower operation temperature to counteract the noise inherent in the system. The suggested design presents an alternative to the more popular detection system whereby the requirement of high operation voltage or low operation temperature can be precluded. This is made possible through the gate capacitance of a Metal Oxide Semiconductor Field Effect Transistor (MOSFET). This thesis …

Single Ion Detection For Mass Spectrometry Using Low Capacitance Mosfets, Matthew Hamblin, Aaron Hawkins

Journal of Undergraduate Research

Mass spectrometry is an important tool for analytical chemistry that allows the chemical composition of a compound to be determined. In order to do so, it separates the compound into ions, and then detects the number of ions of different masses.

The charge on a single ion is very small, making it difficult to measure. In order to overcome this, current mass spectrometers must use methods such as electron multipliers to create a cascading effect of electrons until a measurable charge is reached or cryodetectors that measure the thermal change of an ion hit at low temperatures.¹ Using methods …

Optically Powered Logic Transistor, Hanho Cho

Theses and Dissertations

This thesis presents the modeling and fabrication of a new solid-state device meant to be used for digital logic circuits. Most current logic circuits are based on MOSFETs. The new logic device uses some of the same operating principles, but also relies on optical illumination to provide input power. In order to obtain the desired current-voltage behavior of the new device, the Silvaco (Atlas) device simulation was used to give some insight into the correct doping levels in the semiconductor and device geometries. Prototypes were fabricated on p-type silicon wafers using CMOS fabrication processes including oxide growth, photolithography, precise plasma …

Design Of A High Speed Mixed Signal Cmos Mutliplying Circuit, David Ray Bartholomew

Theses and Dissertations

This thesis presents the design of a mixed-signal CMOS multiplier implemented with short-channel PMOS transistors. The multiplier presented here forms the product of a differential input voltage and a five-bit digital code. A TSMC 0.18 µm MOSFET model is used to simulate the circuit in Cadence Design Systems. The research presented in this thesis reveals a configuration that allows the multiplier to run at a speed of 8.2 GHz with end-point nonlinearity less than 5%. The high speed and low nonlinearity make this circuit ideal for applications such as filtering and digital to analog conversion.