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Impact ionization in biaxial tensile strained Si n and p metal-oxide-semiconductor field-effect transistors is investigated. Despite the smaller band gap and higher carrier mobility in strained Si, no evidence for significantly increased impact ionization is found. This is attributed to the reduced density of states in strained Si, brought about by strain-induced band splitting, limiting the opportunities for scattering. [ABSTRACT FROM AUTHOR]

The transport properties of a two-dimensional hole gas (2DHG), with very high room-temperature drift mobilities, formed in 7.5- (2540 cm2 V-1 s-1) and 20-nm (2940 cm2 V-1 s-1) strained Ge quantum wells of multilayered Si/Si0.33Ge0.67/Ge/Si0.33Ge0.67/Si0.73Ge0.27/Si(001) p-type modulation-doped heterostructures were investigated experimentally in the temperature range of 10–295 K. For both samples the drift mobility of the 2DHG behaves in the same way as the Hall mobility, increases as the temperature decreases. The sheet carrier density of the 2DHG increases with decreasing temperature, which is opposite to the behavior of Hall-effect sheet carrier density. We found that the 2DHG formed in the thicker Ge quantum well has a higher drift mobility at 295 K but a lower one at low temperatures. For both samples the Hall factor increases with decreasing temperature, reaching unity at 10 K, when carriers in parallel conducting layers completely freeze-out. The interpretation of these results is carried out and the scattering mechanisms limiting the 2DHG mobility are discussed. [ABSTRACT FROM AUTHOR]

The incorporation of vacancy clusters and vacancy point defects during the growth of Si/Si[sub 0.64]Ge[sub 0.36]/Si structures has been observed for growth temperatures between 250 °C and 550 °C using positron annihilation spectroscopy. A strong correlation between the electrical characteristics of the structures and the size and concentration of the clusters is observed. For the onset of two-dimensional hole gas behavior, a defect concentration less than 5x10[sup 16] cm[sup -3] is required. A further reduction in concentration below 1x10[sup 16] cm[sup -3] results in optimum electrical performance. The depth at which defects are observed increases with decreasing growth temperature indicating defect mobility during growth or subsequent annealing. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a study which discussed the problem of charge compensation during secondary ion mass spectrometry depth profiling of resistive-layer structures on insulating substrates with reference to BF[sub2] and arsenic-implanted silicon-on-sapphire (SOS). Methods and materials used; Result of BF[sub2] implanted into SOS; Description of the electron stimulated desorption spectra before and after exposure; Characteristics of the boron and fluorine profiles taken from a gold-coated SOS sample.

Studies several Si0.8 Ge0.2 p-channel heterostructures with self-aligned ply-Si metal-oxide-semiconductor gates. Complementary-MOS performance by the low p0MOS field-effect-transistor hole mobility; Development of a fabrication process which has allowed the characterization of a fully pseudomorphic Si/SiGe p-MOS structure from 4.2 K to room temperature.

Examines structural and electrical properties of p+n junctions in silicon by low energy Ga+ implantation. Use of high resolution secondary ion mass spectroscopy; Implantation of molecular species; Annealing data; Sensitivity of the electrical properties of the p+n junctions and its improvement with increasing dose.

We have measured the energy loss rate as a function of carrier temperature for hot holes in Si/Si[sub 0.8]Ge[sub 0.2] quantum wells with sheet carrier densities in the range (3-7)x 10[sub 11] cm[sub -2] at lattice temperatures of 0.35 and 2.0 K. Calculations of the energy loss rate for acoustic phonon deformation potential scattering with coupling constant 4.5 eV show good agreement with measurement. The deformation potential is consistent with a linear interpolation between the bulk Si and Ge values and is in agreement with that deduced from measurements of thermopower in similar samples. In contrast to previous work, we find no evidence for hole coupling to acoustic phonons via a piezoelectric interaction. © 1997 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Discusses a study which investigated deep level distributions in B-doped Si/Si[sub1-x]Ge[subx]/Si layers grown by molecular beam epitaxy using deep level transient spectroscopy. Terms in which broadening in the deep level spectra is discussed; Consequence of the significant band bending; Advantage of the introduction of a heterojunction.

Discusses capacitance measurements on silicon (Si)/Si-germanium (Ge)/Si metastable structures and extraction of valence band offsets and interface charge densities for a variety of Ge compositions. Formula for the charge density for uniformly doped p-type material in the presence of a plane of ionized traps; Validity of the Kroemers analysis; Overview of the fixed charge traps.

Deals with a boron modulation-doped silicon/SiGe heterojunctions grown by molecular beam epitaxy. Subband structure in the quantum well; Mobility calculations; Examination on scattering mechanisms.

Presents a study which explored the imaging of interface dislocations present in a Si[sub0.85]Ge[sub0.15]/silicon sample using the channeling scanning transmission ion microscopy method. Theoretical background; Computational approach; Results.

Boron doped layers were grown by silicon molecular beam epitaxy to establish incorporation processes at temperatures between 900 and 450 °C. For temperatures exceeding 650 °C a surface accumulated phase of boron was formed when doping levels exceeded solid solubility limits. The properties of this surface phase were used to determine solubility limits for boron in silicon. Above 750 °C, the measured equilibrium solubility limit was in the 10[SUP19]-cm[SUP-3] range in good agreement with previously published annealing data and showing a gradual decrease with decreasing temperature. Below 650 °C, the processes leading to the formation of the surface phase were kinetically limited, manifested by a sharp increase in boron solubility limit, with completely activated levels above 1 × 10[SUP20] cm[SUP-3] realized. At intermediate growth temperatures the degree of dopant activation was found to be dependent on growth rate. The stability of fully activated highly-doped boron layers, grown at low temperatures, to ex situ annealing is also discussed. [ABSTRACT FROM AUTHOR]

Presents an overview of a study which examined the formation of buried SiO[sub2] layer by high-dose oxygen implanted into Si/Ge and Si/ Si[sub0.5]Ge[sub0.5] heterostructures by infrared transmission and x-ray photoelectron spectroscopy. Details on silicon on insulator prepared using the separation by implanted oxygen technique; Overview of infrared spectra for as-implanted heterostructures; Method used in obtaining the annealing temperature.