P. Pinard

The saturation of the V3 band formation in Kcl under electron irradiation at room temperature

Abstract It is shown that the V 3 band in Kcl under 30 keV electron irradiation at room temperature grows proportionally to the F band up to concentrations near saturation, the constant of proportionality being independent of radiation intensity and sample origin. This confirms that the F and V 3 centres are complementary defects. The oscillator strength of the V 3 band is calculated.

Influence of Impurities on the Optical Absorption Edge of Gallium Arsenide from 297° to 4°K

To determine accurately the absorption coefficient of GaAs n-doped crystals, we developed an apparatus which permits simultaneous measurement of the coefficients of absorption K and reflection R12 of samples. We have determined with high precision that the absorption edge is exponential, and thus brought to light that not only the concentration of the n impurities, but also their nature changes the slope of the curve log K plotted as a function of the energy. We attribute this to stresses produced in the lattice by impurity atoms. Finally, we note that the reflection coefficients vary greatly from one sample to another.

Transient current trap spectroscopy (TCTS) in GaAs/GaAlAs heterojunctions

Abstract In this paper, we have shown that it is possible to do a full study of deep centers in double heterojunction LED using spectral analysis of transient current. Traps are characterized by their apparent physical parameters (activation energy, concentration, capture cross section).

Influence of stresses on the thermal parameters of chromium-doped GaAs

We have produced dislocations by plastic deformation in a semi‐insulating material (GaAs‐Cr) in order to clarify the part of dislocations in the raw materials used later as substrates in device technology. We have correlated the inhomogeneous distribution of the dislocations revealed by optical microscopy to the thermal conductivity measurements, observed residual stresses after mechanical and thermal treatments by computer aided photoelastometry procedure, calculated and established the stress mapping showing that shear stresses are localized, and observed a relaxation of the material with the time at low temperature.

Gold-related interface states in MOS systems

Abstract We studied the trap levels induced by gold in bulk silicon and at the SiSiO 2 interface. We were principally interested their influence on the bulk and surface generation-recombination rates. The study involved the measurement of the low frequency quasi-static capacitance responses (QSM technique). Analysis of the equilibrium and the non-equilibrium behaviour led to the characterization of the gold-related electronically active sites.

Pulling of Polycrystalline Silicon Ribbons and Residual Stresses Measurement by Computer Aided Photoelasticimetry

The E.P.R. pulling technique, developped for low cost solar cells manufacturing uses the electron bombardment of silicon powder in high vacuum to produce multicrystalline silicon ribbons with columnar elongated grains some millimeter wide. This procedure induces the refining of the starting material but causes residual stresses which are dagaging to the photovoltaic efficiency. Infrared photoelasticimetry, aided by bit image processing, is used to obtain a colour display of the principal stresses over the ribbon and consequently to determinate the best pulling conditions.