B. A. Scott

MOTT TRANSITION FIELD EFFECT TRANSISTOR

A field effect transistor fabricated with an oxide channel has been shown to demonstrate switching characteristics similar to conventional siliconmetal oxide field effect transistors. This device is believed to operate via a Mott metal-insulator transition induced by the gate field, and offers a potential technology alternative for the regime beyond silicon scaling limitations.

ERRATA: GRATING COUPLER FOR EFFICIENT EXCITATION OF OPTICAL GUIDED WAVES IN THIN FILMS

We report a new method of coupling a laser beam to thin‐film optical guided waves which utilizes an optical grating that is made from photoresist and fabricated directly on the film. High efficiency coupling (∼40 %) into a single mode in a glass film is observed.

Growth of YBa2Cu3Ox single crystals

We report a set of conditions for crystal growth of the high‐temperature superconductor YBa2Cu3Ox. The as‐grown single crystals have critical temperatures up to 85 K. Preliminary studies have shown that the transition temperatures can be increased by thermal annealing in oxygen, as in ceramic samples. The crystals are in suitable dimensions for definitive magnetic, optical, and transport measurements.We report a set of conditions for crystal growth of the high-temperature superconductor YBa/sub 2/Cu/sub 3/O/sub x/. The as-grown single crystals have critical temperatures up to 85 K. Preliminary studies have shown that the transition temperatures can be increased by thermal annealing in oxygen, as in ceramic samples. The crystals are in suitable dimensions for definitive magnetic, optical, and transport measurements.

DEFLECTION OF AN OPTICAL GUIDED WAVE BY A SURFACE ACOUSTIC WAVE

The experimental demonstration of deflection of an optical film‐guided wave by a surface acoustic wave is reported. When Bragg conditions are satisfied, 0.18 W acoustic power gives rise to 66% deflection efficiency as measured by the depletion of the incident optical guided wave.

Index of refraction in ‘dirty’ displacive ferroelectrics☆

Abstract We report measurements of the optic index of reflection as a function of temperature, n(T), for several highly disordered ferroelectrics: PLZT ceramic [Pb1−xLax(Zr0.65Ti0.35)1−x/4O3 where x = 0.08] and single crystals of Pb3(MNb2)O9 where M = Zn and Mg. The results are qualitatively different from the unusual displacive ferroelectric behavior and the difference is clearly due to local disorder.

Growth of YBa/sub 2/Cu/sub 3/O/sub x/ single crystals

We report a set of conditions for crystal growth of the high‐temperature superconductor YBa2Cu3Ox. The as‐grown single crystals have critical temperatures up to 85 K. Preliminary studies have shown that the transition temperatures can be increased by thermal annealing in oxygen, as in ceramic samples. The crystals are in suitable dimensions for definitive magnetic, optical, and transport measurements.We report a set of conditions for crystal growth of the high-temperature superconductor YBa/sub 2/Cu/sub 3/O/sub x/. The as-grown single crystals have critical temperatures up to 85 K. Preliminary studies have shown that the transition temperatures can be increased by thermal annealing in oxygen, as in ceramic samples. The crystals are in suitable dimensions for definitive magnetic, optical, and transport measurements.

The tungsten bronze field in the system K2O|Li2O|Nb2O5

A limited portion of the liquidus field and the entire subsolidus stability region has been determined for tungsten bronze-type solid solutions in the K2O|Li2O|Nb2O5 system. The tungsten bronze phase does not occur with completely filled alkali cation sites at the composition K3Li2Nb5O15, but exists exclusively in the high niobia region above the KNbO3|LiNbO3 pseudojoin. Equilibrium relationships defining conditions for the growth of electrooptic crystals, and dielectric, optical, and x-ray measurements establishing the influence of composition on structure and properties are presented and discussed.

Kinetics and mechanism of amorphous hydrogenated silicon growth by homogeneous chemical vapor deposition

A new method of amorphous hydrogenated silicon (a‐Si:H) chemical vapor deposition is presented in which SiH4 is homogeneously decomposed at high temperature and pressure to produce films on low‐temperature substrates having up to 30‐at. % H and properties very similar to plasma‐deposited material. Kinetic studies provide a film growth activation energy of 54 kcal/mole, confirming that SiH2 is the primary gas phase intermediate. A mechanism based on SiH2 chemistry is presented to account for the rapid surface reactions leading to a‐Si:H growth and its possible relevance to the plasma deposition process is emphasized.

Efficient visible photoluminescence in the binary a‐Si:Hx alloy system

We report the photoluminescence (PL) and structural properties of a new class of efficient visible‐light‐emitting semiconductors: low defect density a‐Si:Hx alloys. For films prepared by the (thermal) homogeneous chemical vapor deposition (HOMOCVD) method, new broadband PL develops for x>0.3, reaching a peak emission energy of 2.05 eV for a hydrogen content x=0.66 (40 at. % H). We attribute the wide gaps to the influence of Si–H bonding on the density of states near the valence band edge. We ascribe the new PL process to band‐to‐band recombination from within the alloy band tails. This emission persists at room temperature with an integrated intensity comparable to conventional light‐emitting diode (LED) materials. Qualitatively similar results are obtained for low‐temperature‐deposited rf plasma films prepared from Si2H6, but not from SiH4. We show that a low Si dangling bond concentration is the key factor, for all the different film types, to achieving efficient luminescence.

Layer dependence of the superconducting transition temperature of HgBa2Can−1CunO2n+2+δ

Abstract High-pressure methods have been used to synthesize multiphase compositions in the Hg12{ n −1} n homologous series. The phase assemblages were examined by optical, electron diffraction and X-ray diffraction techniques, and their stoichiometries verified by electron microprobe. Transport and magnetic susceptibility measurements were combined with the results of the phase analysis to establish superconducting transition temperatures for both as-prepared and O 2 - or Ar-annealed materials. It was found that the transition temperature peaks at T c = 134 K for n = 3 and then decreases abruptly for n >4, reaching T c K for n ⪖7.