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Jastrzebski, L.

Publications and source records attributed to Jastrzebski, L..

Defects in silicon effect on device performance and relationship to crystal growth conditions

A relationship between material defects in silicon and the performance of electronic devices will be described. A role which oxygen and carbon in silicon play during the defects generation process will be discussed. The electronic properties of silicon are a strong function of the oxygen state in the silicon. This state controls mechanical properties of silicon efficiency for internal gettering and formation of defects in the device's active area. In addition, to temperature, time, ambience, and the cooling/heating rates of high temperature treatments, the oxygen state is a function of the crystal growth process. The incorporation of carbon and oxygen into silicon crystal is controlled by geometry and rotation rates applied to crystal and crucible during crystal growths. Also, formation of nucleation centers for oxygen precipitation is influenced by the growth process, although there is still a controversy which parameters play a major role. All these factors will be reviewed with special emphasis on areas which are still ambiguous and controversial.

Jastrzebski, L.

Float zone space processing rationale

The role of float zone silicon in integrated circuits is surveyed. The problem of oxygen thermal donors and their inhomogeneous distribution is predicted to be a critical issue.

Jastrzebski, L.

Problems with state-of-the-art float zone silicon

An application in which CCD optical imaging arrays with 250,000 elements are fabricated from the best commercially available float zone Si is described. Two image defects are described which appear to be related to the starting material. The striation effect appears to be caused by resistivity and recombination center variations. Up to 30 percent variations in resistivity was measured across a sample.

Jastrzebski, L.

Determination of carrier concentration and compensation microprofiles in GaAs

Simultaneous microprofiling of semiconductor free carrier, donor, and acceptor concentrations was achieved for the first time from the absolute value of the free carrier absorption coefficient and its wavelength dependence determined by IR absorption in a scanning mode. Employing Ge- and Si-doped melt-grown GaAs, striking differences were found between the variations of electron concentration and those of ionized impurity concentrations. These results showed clearly that the electronic characteristics of this material are controlled by amphoteric doping and deviations from stoichiometry rather than by impurity segregation.

Jastrzebski, L.

Liquid-phase electroepitaxy - Dopant segregation

A theoretical model is presented which accounts for the dopant segregation in liquid-phase electroepitaxy in terms of dopant transport in the liquid phase (by electromigration and diffusion), the growth velocity, and the Peltier effect at the substrate-solution interface. The contribution of dopant electromigration to the magnitude of the effective segregation coefficient is dominant in the absence of convection; the contribution of the Peltier effect becomes significant only in the presence of pronounced convection. Quantitative expressions which relate the segregation coefficient to the growth parameters also permit the determination of the diffusion constant and electromigration mobility of the dopant in the liquid phase. The model was found to be in good agreement with the measured segregation characteristics of Sn in the electroepitaxial growth of GaAs from Ga-As solutions. For Sn in Ga-As solution at 900 C the diffusion constant was found to be 4 x 10 to the -5 sq cm/s and the electromigration velocity (toward the substrate with a positive polarity 2 x 10 to the -5 cm/s current density of 10 A/sq cm.

Lagowski, J.

Outdiffusion of recombination centers from the substrate into LPE layers - GaAs

Experimental results are presented showing that outdiffusion of recombination centers from the GaAs substrate into the epitaxial layer takes place during growth. Such outdiffusion decreases the carrier lifetime in the epitaxial layer to much lower values than the radiative recombination limit. Furthermore, it introduces a lifetime gradient across the epitaxial layer which depends critically on the growth velocity and thermal treatment. High rates of growth (such as those attainable in electroepitaxy) and high cooling rates can minimize the adverse effects of normally available substrates on the epitaxial layers; however, good quality substrates are essential for the consistent growth of device quality layers.

Jastrzebski, L.

Electron mobility and free-carrier absorption in GaAs - Determination of the compensation ratio

Theoretical calculations of electron mobility and free-carrier absorption in n-type GaAs at room temperature were carried out taking into consideration all major scattering processes. It was found that satisfactory agreement between theoretical and experimental results on free-carrier absorption is obtained only when the effect of compensation is quantitatively taken into account. In conjunction with experimental studies it is shown that the electron mobility (for n greater than 10 to the 15th per cu cm) and free-carrier absorption (for n greater than 10 to the 16th per cu cm) are sufficiently sensitive to the ionized impurity concentration to provide a reliable means for determining the compensation ratio. Convenient procedures are presented for the determination of the compensation ratio from the free-carrier absorption coefficient and from the computed values of room-temperature electron mobility. Values of the compensation ratio obtained by these two procedures are in good agreement provided the carrier-concentration variations in the material are not appreciably greater than 10%.

Walukiewicz, W.

Present status of GaAs

An extensive literature survey on GaAs was carried out for the period December 31, 1970, to December 31, 1977. The increasing interest in GaAs device structures increased steadily during that period. The leading research and development centers and the specific areas of interest were identified. A workshop on GaAs was held in November 1977 to assess the present status of melt-grown GaAs and the existing needs for reliable chemical, structural, and electronic characterization methods. It was concluded that the present available bulk GaAs crystals are of poor quality and that GaAs technology is lagging demonstrated or potentially feasible GaAs devices and systems.

Gatos, H. C.