George Elwood Smith

CHARGE COUPLED 8‐BIT SHIFT REGISTER

An 8‐bit shift register has been developed based on the charge‐coupled device concept. The device configuration is essentially that of a linear array of 26 closely spaced MOS capacitors with a p‐n junction at either end. A packet of charge is inserted into the first capacitor from one of the p‐n junctions and then transferred down the array in a potential well created by sequential pulsing of the electrode potentials. A high‐charge transfer efficiency of greater than 99.9% per electrode has been obtained in this device for transfer times of 2μ sec. The use of the device as an 8‐bit shift register and a line imaging device are demonstrated thereby further verifying the charge‐coupled device concept and showing the basic feasibility of developing charge‐coupled devices for shift registers, logic operations, and optical imaging applications.

Conductively connected charge-coupled device

A new kind of charge-coupled device, the conductively connected charge-coupled device (C4D) has been built and operated. This device is formed by providing self-aligned, source-drain diffusions (or implants) between adjacent, refractory electrodes of a two-phase, ion implanted-barrier CCD. These implants eliminate the inherently unstable exposed channel region presently found in CCDs with coplanar gates, without resorting to overlapping gates. Shift registers ranging from 16 to 128 b in length were evaluated and in spite of low mobilities (80 cm2/V.s) and low barrier heights (2-3 V), incomplete transfer losses of 0.2 percent per transfer were measured at 1 MHz clock frequency. Fabrication has been demonstrated to be quite compatible with p-channel refractory gate IGFET technology, and because the sensitive interelectrode region of the C4D is heavily doped, these devices should show the same reliability as conventional circuits made with the same technology.

Alfvén wave propagation in bismuth: quantum oscillations of the Fermi surface

Alfveh wave propagation in single crystal bismuth has been studied as a function of magnetic field to 105 kilogauss for frequencies between 13 and 18 kMc/sec. Small deviations from a linear dependence of wave velocity on magnetic field are found and are interpreted as quantum oscillations in the mass density of carriers. Theory and experiment are compared for the magnetic field along a bisectrix axis and along a two-fold axis. Good agreement is found for the first case, but significant discrepancies exist for the magnetic field along a two-fold axis.

The effective g-factor of holes in bismuth

Measurements have been made of the Shubnikov-de Haas effect in bismuth at 1.5°K and fields up to 88 kG. The effect consists of oscillations in the resistance as a function of magnetic field. The oscillations result from the quantization of the transverse energy of the carriers in a magnetic field. From the positions of the oscillations, one can obtain information concerning the band structure. In the present investigation, we have obtained values of the g-factors for holes in bismuth and have determined the variation of Fermi energy as a function of magnetic field. First an outline of the theory will be presented and then the results.