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Title: Optimization of germanium MOSFET fabrication processes
Author: Gajula, Durga Rao
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2013
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As silicon MOSFETs have reached their saturation limits due to aggressive scaling, high mobility channel materials like germanium are offering a future generation of semiconductor materials. Germanium's smaller band-gap broadens the optical absorption spectrum, and its low melting point considerably reduces the process temperature compared with silicon. However its unstable native oxide, large diffusion constant of n-type dopants, high series resistance of metal contacts on germanium, susceptibility to implantation damage, Fermi-level pinning of metal contacts on n-type source/drain regions, poor-quality interfaces between germanium and high-k dielectrics, etc. are compromising the performance of germanium MOSFETS. Implant-less nickel germanide source and drain p-channel MOSFETs were successfully fabricated at a low thermal budget. A effective hole mobility of -340 cm2/Vsec was measured on nickel germanide source/drain p-MOSFETs with Hf02/GeOxNy as gate dielectric. The Fermi level of aluminium contacts on germanium was successfully unpinned by using atomic layer deposited layers. A barrier height from ~O.7e V for Al contacts on n-Ge to a value of 0.28 e V was realized with insertion of a thin alumina interfacial layer (28.5 A)
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available