Resistivity Striations Research Articles

CCD development for the Dark Energy Spectroscopic Instrument

We describe research and development efforts directed towards the production of 4 k × 4 k, 15 μm-pixel, fully depleted CCDs for the Dark Energy Spectroscopic Instrument (DESI). The requirements for DESI include the spectroscopic characterization of large numbers of faint galaxies at high redshift. The identification of the type and the determination of the redshift of the targeted galaxies require the use of thick, fully depleted CCDs with high quantum efficiency at near-infrared wavelengths. We describe our work to improve the CCD performance in terms of quantum efficiency and read noise. We also discuss efforts to reduce the level of image-distortion effects that have been observed on previous CCDs that are due to resistivity striations in the starting silicon and periodic errors in the photomasks used to produce the CCDs.

Effect of swirl‐like resistivity striations in n+‐type Sb doped Si wafers on the properties of Ag/porous silicon SERS substrates

AbstractPorous silicon (PS) represents the prospective template for the fabrication of metal/PS nanostructures. However n+‐type Sb doped Si Czochralski wafers widely used to fabricate PS may contain resistivity striations and as‐grown microdefects with specific spiral distribution which influence Si dissolution during the formation of PS by anodizing. This may strongly affect on the PS microstructure and repeatability of metal/PS properties causing an increase of risk of a device failure. In the present research we studied the morphology and SERS‐activity of Ag/PS nanostructures formed by Ag immersion deposition on PS. SEM investigation revealed unequal distribution of pore diameters in the surface regions of PS which corresponds to spiral swirl‐like distribution of resistivity revealed in Si wafer by anodizing. Morphological changes of Ag deposit on spiral areas were found to cause decreasing of intensity of SERS signal. Additional implantation of Sb ions followed by high temperature annealing has shown to be a technique to improve homogeneity of Ag/PS SERS substrates. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Application of a scanning photon microscope to non-destructive detection of resistivity striations in a silicon wafer

Resistivity striations in a strongly inverted FZ grown n-type silicon wafer are non-destructively detected by photovoltage imaging, in which a 2 kHz AC surface photovoltage, induced by the irradiation of a chopped blue (peaking at 448 nm) photon beam with 30 mu W, is mapped as a 512*480 pixel black and white image. The image contrast is due to the interface trap distribution associated with inhomogeneous dopant concentration.

Avalanche breakdown characteristics of punchthrough diodes

A theoretical investigation of the avalanche breakdown characteristics of punchthrough diodes is carried out and a comparison made with the nonpunchthrough diodes. It is shown that the former have harder breakdown characteristics and a sharper knee for a given breakdown voltage. In addition, punchthrough diodes have a lower temperature coefficient of breakdown voltage, a lower space-charge resistance, a negligible sensitivity of breakdown voltage to resistivity striations in single crystal wafers, and breakdown due to avalanche mechanism up to lower breakdown voltages. Though these positive features suggest that punchthrough diodes are superior in performance to nonpunchthrough diodes for applications such as voltage regulators etc., the final assessment will depend on a more critical evaluation of the reliability against burn out and instability.

Investigation of Breakdown and Resistivity Striations in High‐Voltage Silicon Diodes

The breakdown behavior of high‐voltage diodes prepared from silicon wafers that were cut parallel to the rod axis was observed by means of the infrared breakdown radiation. The breakdown patterns were striated and could be correlated to spreading resistance measurements on a microscopic scale. It could be confirmed experimentally that the breakdown in material with resistivity variations not only depends on the absolute resistivity value at each location, but also to a large extent on the wave form and the period of the variations. Only in diodes in which the microscopic resistivity variations had high amplitudes and a distinct periodicity with wavelengths longer than the extent of the space charge region did individual minima lead to individual clearly separated breakdown lines.

Infrared observation of the breakdown behavior of high-voltage p-n junctions and p-n-p structures in silicon

It is shown that the radiation emitted at breakdown from large-area high-voltage p-n junctions and from p-n-p structures can be detected using an infrared image converter in conjunction with a three-stage image intensifier. In the example given, the patterns of the emitted light consist of segments of circles and spirals, indicating an inhomogeneous breakdown across the area. The inhomogeneous breakdown is attributed to resistivity striations inside the silicon. The infrared radiation emitted from the p-n-p structure was more intense by approximately one order of magnitude than that of the p-n junction, the additional emission being recombination radiation generated in front of the forward-biased emitter.

Scanning electron micrograph using beta-conductive signal

A pulsed electron beam was used to get scanning electron microscope images. A d.c. voltage was applied to an n-Ge bar which had resistivity striations (Munakata), and images of the electric field distribution in the bar were obtained.

Galvanomagnetic properties of recrystallized dendritic InSb films

The galvanomagnetic properties of monophase, dendritic, preferentially oriented InSb films grown from a non-stoichiometric melt containing an excess of Sb, are described. Such films are n-type and have the following properties: a Hall coefficient of the same order of magnitude as that of bulk polycrystalline InSb, an electron mobility which is thickness dependent reaching a value μ e = 4 × 10 4 cm 2/V-sec in films 3 μm thick, a magnetoresistance which is quadratic in H for μH < 1 and is linear in H for μH > 1, inhomogeneity fluctuations and resistivity striations which lead to geometrical effects larger than those associated with macroscopic length to width ratios of rectangular specimens. The charge carrier density in these films is between 5 × 10 16 electrons/cm 3 and 2 × 10 16 electrons/cm 3 near 300°K. Experimental data suggests that lattice scattering, in combination with dislocation scattering in accordance with the Dexter-Seitz model, accounts for the temperature dependence of the electron mobility above 200°K. Calculated dislocation densities in films are of the order of 10 9. It is suggested that dislocation scattering represents a significant mobility limiting process in evaporated or recrystallized InSb films.

Detection of Resistivity Striations in a Ge Crystal with an Electron Beam

Detection of Resistivity Striations in a Ge Crystal with an Electron Beam

Avalanche Effects in Silicon p—n Junctions. II. Structurally Perfect Junctions

The fabrication of a planar guard ring diode which exhibits uniform microplasma-free breakdown is described. Discrepancies are discussed between the behavior of these junctions and those reported by Batdorf et al. and Chynoweth, including results showing extremely hard V-I characteristics associated with uniform avalanche breakdown. Experimental evidence is presented which confirms Shockley's theory in which the breakdown behavior is predicted from the Poisson distribution of impurities within the space-charge layer. The photomultiplication technique as described in Paper I is applied to uniform p—n junctions. The linearity of 1/M vs V, as predicted by theory, was verified for values of M between 1.6 and 500. For higher values, the multiplication curves deviate from a straight line. In this higher range they are in good agreement with the pulse-multiplication model developed in Paper I. Light emission patterns from these junctions are shown and a correlation between these patterns and crystal properties is discussed. The effects of resistivity striations in the silicon single crystals is shown to have a strong effect on breakdown areas and no effects of dislocations and oxygen on uniformity are found. From capacity and multiplication measurements a value for the breakdown field of EB=445±25 kV/cm was obtained for a 32-V junction.

Resistivity Striations in Germanium Single Crystals

Resistivity striations resulting from periodic distribution of impurities have been observed in single crystals of germanium grown horizontally. The period of the striations ranges from 0.1 to 0.6 mm, depending upon growth conditions. It is proportional to the average growth rate and inversely proportional to the temperature gradient with in the crystal near the solid-liquid interface. This relation can be explained by assuming the supercooled state in the course of germanium crystal growth by the zone leveling technique. By the repeated supercooling and recovery from it, the crystalization proceeds periodically, resulting in the periodic change of the transient growth rate and the periodic segregation of impurities.

Resistivity Striations in Germanium Crystals

Germanium metal, both single crystalline and polycrystalline, is frequently found to contain sharp fluctuations in impurity concentration. These are superimposed on the gradual variations expected as the result of ordinary segregation processes. A rather simple technique for detecting fluctuations of this kind has been developed. It is more sensitive than resistivity scanning and does not involve the use of radioactive tracers. This technique has been applied to a number of samples. The origin, value, and elimination of these fluctuations are discussed briefly.