Investigation of the electron transport and electrostatics of nanoscale strained Si/Si/Ge heterostructure MOSFETs

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.Includes bibliographical references (p. 125-138).This thesis presents work aimed at investigating the possible benefit of strained-Si/SiGe heterostructure MOSFETs designed for nanoscale (sub-50-nm) gate lengths with the aid of device fabrication and electrical measurements combined with computer simulation. MOSFET devices fabricated on bulk-Si material are scaled in order to achieve gains in performance and integration. However, as device dimensions continue to scale, physical constraints are being reached that may limit continued scaling and/or the gains in performance from scaling. In order to continue the benefits of scaling, a possible solution is to change to a strained-Si/SiGe material system where enhanced electron mobility of 1.7-2X has been demonstrated for long-channel n-type devices. The electron mobility enhancement observed for long channel length devices may not be the same for devices with nanoscale gate length. In particular, increased channel doping, which is required to control short-channel effects can result in degraded transport characteristics. In this work, the impact of high channel doping on mobility enhancements in strained-Si n-MOSFETs is investigated experimentally. Increased channel doping will increase Coulomb scattering interactions increasing its influence on the overall mobility. Electron transport models were calibrated using experimental data for both strained and un-strained Si devices for various channel doping concentrations. The transport models were then used to investigate, by computer simulation, the performance enhancement of nanoscale strained Si devices for equivalent off-current.by Hasan M. Nayfeh.Ph.D

Correlation of silicon microroughness on electrical parameters of SOI-AS (silicon-on-insulator with active substrate)

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.Includes bibliographical references (leaves 83-86).by Hasan M. Nayfeh.M.S

Demonstration of quantum volume 64 on a superconducting quantum computing system

We improve the quality of quantum circuits on superconducting quantum computing systems, as measured by the quantum volume, with a combination of dynamical decoupling, compiler optimizations, shorter two-qubit gates, and excited state promoted readout. This result shows that the path to larger quantum volume systems requires the simultaneous increase of coherence, control gate fidelities, measurement fidelities, and smarter software which takes into account hardware details, thereby demonstrating the need to continue to co-design the software and hardware stack for the foreseeable future.Comment: Fixed typo in author list. Added references [38], [49] and [52