Analytical Design and Numerical Verification of p-Channel Strained Silicon-Germanium Hetero MOSFET
AuthorGopal, Mohan Krishnan
KeywordsAnalytical design program for hmosfet
hetero junction mosfet (hmosfet)
strain induced effects in silicon germanium
AdvisorBrews, John R.
Committee ChairBrews, John R.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractSilicon Germanium (Si1-xGex) is an alloy semiconductor that has caught considerable attention of the semiconductor industry in the past decade. Effects of strain in thin films are the reason for this. Strain leads to considerable deformation of bands providing enhanced mobility for both electrons and holes. Another important aspect of SiGe is the reduction of band gap. This makes band gap engineering feasible in all silicon technology. Yet another attractive point is the adaptability and compatibility of SiGe to silicon process technology.In CMOS circuits the p-channel MOSFET needs more than double the area of the n-channel MOSFET due to the lower mobility of holes in silicon. Hence a p-channel hetero MOSFET (HMOSFET) is chosen as the object of this dissertation.A simple general device structure that can provide considerable enhancement in performance, compared to a conventional MOSFET, is selected. A one dimensional Poisson equation is solved for this hetero junction device. Using these results an Excel spreadsheet is used as a tool to design a complete analytical program that can provide internal as well as terminal parameters of this device. The analytical program is tested by comparing the results with ISE-TCAD numerical device simulator results. The results were found to match very well. This analytical program yields results in a fraction of the time compared to numerical programs. For the device of choice variable parameters are identified. It is found that these parameters are interconnected in many ways and trade offs between them need to be applied.From the front end of the spreadsheet input parameters can be varied and parameters like potentials, hole density and terminal characteristics can be plotted very easily while simultaneously computing other parameters like threshold voltage and saturation current.The main contribution of this dissertation research is(1) Development of a very efficient and accurate analytical program to interactively design and optimize a p-channel HMOSFET(2) A detailed understanding and explanation of various design parameters, their implications, interdependency and trade offs(3) Study and explanation of certain special characteristics ofp-HMOSFET like dual threshold voltage, low off-currents, structural limitations etc.
Degree ProgramElectrical & Computer Engineering