S. J. Sessions

Bio: S. J. Sessions is an academic researcher from University of Oxford. The author has contributed to research in topics: Cyclotron resonance & Effective mass (solid-state physics). The author has an hindex of 2, co-authored 3 publications receiving 86 citations.

Cyclotron resonance and the magnetophonon effect in GaxIn1−xAsyP1−y

Abstract: Cyclotron resonance and the magnetophonon effect have been used to measure the effective mass as a function of alloy composition for GaxIn1−xAsyP1−y samples grown lattice matched to InP. Values of ωτ of up to 6 allow an accurate measurement of effective mass, which is found to depend linearly upon alloy composition y with the relation m*/m0=0.080−0.039y. The observation of shallow impurity transitions in a quaternary alloy is also reported.

Shallow donor spectroscopy in Ga x In 1-x As y P 1-y

Abstract: Transitions between the 1s and 2p levels of shallow hydrogenic donors have been observed in two samples of high purity Ga x In 1-x As y P 1-y by infrared photoconductivity and transmission. The magnetic field dependence of the shallow hydrogenic levels is found to be very accurately predicted by the use of an effective Rydberg constant R* = R_{0}(m*/m_{0}\epsilon_{0}^{2}) where the dielectric constant (e 0 ) has been determined by interpolation of the values for the alloy constituents, and the effective mass m*/m_{0} is given by the linear interpolation m*/m_{0} = 0.08 - 0.039y . At high magnetic fields, the 2p+ level is found to show polaron pinning to the LO phonon associated with a "Ga x In 1-x As"-like alloy.

Identification of contaminating donors in III–V compounds by far-infrared laser magneto-optical studies

Abstract: The chemical shifts of the is-2p Zeeman transitions between donor states in n-GaAs and n-InP have been studied in samples from numerous sources In the best samples of InP eleven separate peaks were observed The approximate locations of the S and Si components have been established using backdoped samples The only radically different set of residual donors in InP is produced by bulk growth

Band parameters for III–V compound semiconductors and their alloys

Abstract: We present a comprehensive, up-to-date compilation of band parameters for the technologically important III–V zinc blende and wurtzite compound semiconductors: GaAs, GaSb, GaP, GaN, AlAs, AlSb, AlP, AlN, InAs, InSb, InP, and InN, along with their ternary and quaternary alloys. Based on a review of the existing literature, complete and consistent parameter sets are given for all materials. Emphasizing the quantities required for band structure calculations, we tabulate the direct and indirect energy gaps, spin-orbit, and crystal-field splittings, alloy bowing parameters, effective masses for electrons, heavy, light, and split-off holes, Luttinger parameters, interband momentum matrix elements, and deformation potentials, including temperature and alloy-composition dependences where available. Heterostructure band offsets are also given, on an absolute scale that allows any material to be aligned relative to any other.

GaAs, AlAs, and AlxGa1−xAs: Material parameters for use in research and device applications

Abstract: The Al x Ga1−x As/GaAs heterostructure system is potentially useful material for high‐speed digital, high‐frequency microwave, and electro‐optic device applications Even though the basic Al x Ga1−x As/GaAs heterostructure concepts are understood at this time, some practical device parameters in this system have been hampered by a lack of definite knowledge of many material parameters Recently, Blakemore has presented numerical and graphical information about many of the physical and electronic properties of GaAs [J S Blakemore, J Appl Phys 5 3, R123 (1982)] The purpose of this review is (i) to obtain and clarify all the various material parameters of Al x Ga1−x As alloy from a systematic point of view, and (ii) to present key properties of the material parameters for a variety of research works and device applications A complete set of material parameters are considered in this review for GaAs, AlAs, and Al x Ga1−x As alloys The model used is based on an interpolation scheme and, therefore, necessitates known values of the parameters for the related binaries (GaAs and AlAs) The material parameters and properties considered in the present review can be classified into sixteen groups: (1) lattice constant and crystal density, (2) melting point, (3) thermal expansion coefficient, (4) lattice dynamic properties, (5) lattice thermal properties, (6) electronic‐band structure, (7) external perturbation effects on the band‐gap energy, (8) effective mass, (9) deformation potential, (10) static and high‐frequency dielectric constants, (11) magnetic susceptibility, (12) piezoelectric constant, (13) Frohlich coupling parameter, (14) electron transport properties, (15) optical properties, and (16) photoelastic properties Of particular interest is the deviation of material parameters from linearity with respect to the AlAs mole fraction x Some material parameters, such as lattice constant, crystal density, thermal expansion coefficient, dielectric constant, and elastic constant, obey Vegard’s rule well Other parameters, eg, electronic‐band energy, lattice vibration (phonon) energy, Debye temperature, and impurity ionization energy, exhibit quadratic dependence upon the AlAs mole fraction However, some kinds of the material parameters, eg, lattice thermal conductivity, exhibit very strong nonlinearity with respect to x, which arises from the effects of alloy disorder It is found that the present model provides generally acceptable parameters in good agreement with the existing experimental data A detailed discussion is also given of the acceptability of such interpolated parameters from an aspect of solid‐state physics Key properties of the material parameters for use in research work and a variety of Al x Ga1−x As/GaAs device applications are also discussed in detail

Material parameters of In1−xGaxAsyP1−y and related binaries

Abstract: Various models for calculation of physical parameters in compound alloys are discussed and the results for In1−x Gax Asy P1−y quaternaries are presented. The model used is based on a linear interpolation scheme, and therefore necessitates known values of the parameters for the related binary and ternary alloys. The material parameters considered in the present study can be classified into the following eleven groups: (1) lattice constant and crystal density, (2) thermal expansion coefficient, (3) electronic‐band structure, (4) external perturbation effect on the lowest‐direct gap, (5) effective mass, (6) dielectric constant, (7) Frohlich coupling parameter, (8) elastic properties, (9) piezoelectric properties, (10) deformation potential, and (11) excitonic effect. Of particular interest is the deviation of material parameters from linearity with respect to the alloy composition. It is found that the present model provides generally acceptable parameters, in good agreement with the existing experimental da...

Density-matrix theory of semiconductor lasers with relaxation broadening model - Gain and gain-suppression in semiconductor lasers

Abstract: The density-matrix theory of semiconductor lasers with relaxation broadening model is finally established by introducing theoretical dipole moment into previously developed treatments. The dipole moment is given theoretically by the k . p method and is calculated for various semiconductor materials. As a result, gain and gain-suppression for a variety of crystals covering wide wavelength region are calculated. It is found that the linear gain is larger for longer wavelength lasers and that the gain-suppression is much larger for longer wavelength lasers, which results in that single-mode operation is more stable in long-wavelength lasers than in shorter-wavelength lasers, in good agreement with the experiments.

Density-matrix theory of semiconductor lasers with relaxation broadening model-gain and gain-suppression in semiconductor lasers

Abstract: The density-matrix theory of semiconductor lasers with relaxation broadening model is finally established by introducing theoretical dipole moment into previously developed treatments. The dipole moment is given theoretically by the k . p method and is calculated for various semiconductor materials. As a result, gain and gain-suppression for a variety of crystals covering wide wavelength region are calculated. It is found that the linear gain is larger for longer wavelength lasers and that the gain-suppression is much larger for longer wavelength lasers, which results in that single-mode operation is more stable in long-wavelength lasers than in shorter-wavelength lasers, in good agreement with the experiments.