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Varying Ge composition up to 57% and p+ tunnel-junction (source) doping concentration are employed to analyze strained pseudomorphic Si/[Si.sub.1-x][Ge.sub.x]/Si gate-controlled band-to-band tunneling (BTBT) devices. The results showed that the switching characteristics of TFETs could be significantly improved by controlling the strained-SiGe bandgap of 0.55 eV.

The mechanism responsible for the dependence of hole mobility on SiGe channel layer thickness is investigated for channel thickness of 1.8nm. Due to the combination of phonon and interface scattering the mobility is found to degrade for channel thickness below 4nm and for SiGe films of channel thickness greater than 2.8nm the scattering is not very significant.

The fabrication and analysis of n- and p-MOSFETs in novel ultrathin-body (UTB) strained semiconductor heterostructure-on-insulator (HOI), achieved by epitaxial growth, bonding and transfer of strained layers, is described. Increased OFF-state leakage currents are seen in HOI compared to strained Si directly on insulator (SSDOI) and unstrained silicon-on-insulator (SOI) and for a 4-nm-thick buried SiGe layer, leakage is reduced relative to devices with thicker SiGe channels.

Study was conducted to investigate the impact of processing factors such as ion implantation and rapid thermal annealing on mobility enhancement in strained-Si n-channel metal-oxide-semiconductor field-effect transistors (n-MOSFETs). Electron mobility enhancement is presented to degrade considerably when the implant dose is above a certain critical dose for a given annealing condition.

A physically based analytic model for the threshold voltage Vt of long-channel strained-Si-Si1-(sub x)Ge(sub x) n-MOSFETs is given and confirmed with the help of numerical simulations for a wide range of channel doping concentration, gate-oxide thickness, and strained-Si layer thicknesses. The threshold voltage difference between strained- and unstrained-Si devices increases with channel doping but as such the increase is mitigated by gate oxide thickness reduction.

The study stated that Hole mobility is characterized in P-MOSFETs with a layered substrate consisting of tensile strained Si cap on a compressively strained Si (sub 0.4) Ge (sub 0.6) buried layer grown pseudomorphically to a relaxed. The analysis also founded that mobility is a function of inversion carrier density, measured mobility curves can be matched consistently with a single set of mobility-carrier-density relationship.

The impact of heavy doping and reduced density of states in Si1(sub -y)C(sub y) compared to Si on the extraction of the energy band offset, and on the collector current of p-n-p HBTs. A guide to further investigation of HBT designs aspects in the Si/Si1(sub -y)C(sub y) material system is provided by the study.

Conventional admittance spectroscopy is based on the measurement of pn junction admittance or Schottsky diodes made on a substrate. The principle of admittance spectroscopy is applied for the first time ever to the measurement of MOS capacitors manufactured on Si/Si sub 1-xGe sub x/Si double heterostructures. The method was verified through experimentation. A new feature of this MOS capacitor measurement method is that two hetero-interfaces of a double heterostructure can be evaluated separately by controlling the gate voltage.

Deep submicron strained-Si n-MOSFET's fabrication was undertaken on strained Si/relaxed Si0.8Ge0.2 heterostructures.