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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 Boltzmann-Matano analysis is employed to study and analyze the Si-Ge interdiffusion in strained Si or strained SiGe heterostructures, which are used for enhanced mobility metal-oxide-semiconductor field-effect transistors. The analysis reveals that the threading dislocation densities do not have much effect on the Si-Ge interdiffusion in such structures.

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.

Strained Si/strained Si0.3Ge0.7/relaxed Si0.7Ge0.3 heterostructure p-type metal-oxide-semiconductor field-effect transistors (MOSFETs) with high mobility and low leakage are demonstrated using laser spike annealing, despite a strained Si0.3Ge0.7 channel thickness that is two times the equilibrium critical thickness. Measured hole mobility is enhanced four times for Si0.3Ge0.7 channel MOSFETs relative to Si control devices, at an inversion charge density of 1013 cm-2. For supercritical thickness strained SiGe channel films, the use of laser spike annealing allows source/drain annealing at significantly higher temperatures than is possible with rapid thermal annealing (e.g., 975 versus 800 °C), while achieving superior leakage characteristics. For laser spike annealing temperatures above 1000 °C, mobility is found to degrade due to partial relaxation and dislocation formation in the Si0.3Ge0.7 channel. [ABSTRACT FROM AUTHOR]

We have investigated the mechanism of crystallite nucleation and growth in prepatterned nanoscale α-Si pillars using transmission electron microscopy. The number of α-Si pillars that crystallize during annealing depends upon the pillar diameter and the density of nucleation sites at the α-Si/oxide interface, in the as-deposited film. These nucleation sites are presumed to be clusters of atoms exhibiting short-range order that are formed during the initial deposition of α-Si. Their density depends upon the specific deposition conditions. The density of nucleation sites is extracted from the measured pillar crystallization statistics using a Poisson distribution model. It is also observed that the orientation dependence of the crystal growth rate enhances the formation of a single grain inside each pillar. Significant reduction of defect density is achieved with high temperature annealing of sub-100-nm pillars where the surface to bulk ratio is high. [ABSTRACT FROM AUTHOR]

Si–Ge interdiffusivity in epitaxial strained Si/Si1-yGey/strained Si/relaxed Si1-x0Gex0 heterostructures is extracted for Ge fractions between 0 and 0.56 over the temperature range of 770–920 °C. Boltzmann-Matano analysis is applied to determine interdiffusivity from diffused Ge profiles in strained Si/relaxed Si1-x0Gex0 heterostructures [L. Boltzmann, Wiedemanns Ann. Phys. 53, 959 (1894) and C. Matano, Jpn. J. Phys. 8, 109 (1933)]. A model for the interdiffusivity suitable for use in the process simulator TSUPREM-4 is constructed. Si–Ge interdiffusivity increases by 2.2 times for every 10% increase in Ge fraction for interdiffusion in strained Si/relaxed Si1-x0Gex0 samples. Significantly enhanced Si–Ge interdiffusion is observed for Si1-yGey layers under biaxial compressive strain. Si–Ge interdiffusivity is found to increase by 4.4 times for every 0.42% increase in the magnitude of biaxial compressive strain in the Si1-yGey, which is equivalent to a decrease in the Ge percentage in the substrate by 10 at. %. These results are incorporated into an interdiffusion model that successfully predicts experimental interdiffusion in various SiGe heterostructures. The extracted activation energy and prefactor for the interdiffusivity are 4.66 eV and 310 cm2/s, respectively, for the temperature and Ge fraction ranges of this study. Threading dislocation densities on the order of 107 cm-2 are shown to have negligible effect on Si–Ge interdiffusion in Si/Si0.69Ge0.31 structures. Substituting the strained Si layers surrounding the Si1-yGey peak layer with SiGe layers is shown to have little effect on the Si–Ge interdiffusivity. The implications of these findings for the design and process integration of enhanced mobility strained Si/strained SiGe metal-oxide-semiconductor field-effect transistors are discussed. [ABSTRACT FROM AUTHOR]

Laser spike annealing is used to study the strained Si/strained [Si.sub.0.3][Ge.sub.0.7]/relaxed [Si.sub.0.7][Ge.sub.0.3] heterostructure p-type metal-oxide-semiconductor field-effect transistors (MOSFETs) with high mobility and low leakage. The mobility was observed to degrade due to partial relaxation and dislocation formation in the [Si.sub.0.3][Ge.sub.0.7] channel at laser spike annealing temperatures above 1000 degree Celsius.

The mechanism of crystalline nucleation and growth in prepatterned nanoscale [alpha]-Si pillars is investigated by using transmission electron microscopy. The results have shown that the orientation dependence of the crystal growth rate has increased the formation of a single grain inside each pillar.