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Complex conductivities of YBa2Cu3O7 high‐temperature superconducting thin films were measured from 80 to 111 GHz using quasi‐optical techniques. From transmission measurements, a peak was obtained in σ1 versus temperature. Measurements of the frequency dependence of this peak position found it shifted to higher temperatures with increasing frequency. The data for both σ1 and σ2, as a function of frequency, were fitted using a BCS/effective medium model. This fit indicates that the observed peak in σ1 is a result of the temperature dependence of the carrier mean free path combined with effects resulting from the granularity of the films.

Epitaxial YBa2Cu3O7−x(YBCO) films were grown on SrTiO3‐buffered (100) MgO substrates by pulsed laser deposition. The SrTiO3 layer of about 500 A thick serves a dual purpose to provide a better lattice match to the YBCO films as well as a diffusion barrier to prevent interaction between YBCO and MgO. These YBCO films exhibit excellent structural, electrical, and microwave properties with Tc≳89 K and Tc=2.9×106 A/cm2 at 77 K (1×106A/cm2 at 84 K). X‐ray pole figure measurements showed that over 99.92% of the volume fraction of the c‐axis oriented film has the a‐b axis aligned parallel to the [010] and [001] direction of the substrate.

We report the first mm wave passive component made with high temperature superconducting thin films. Microstrip bandpass filters, with bandwidth of 2.2 GHz and a center frequency of 55 GHz, were made using YBa2Cu3O7−x filter patterns on MgO substrates with Au ground planes. The best results were obtained for a film grown with a thin SrTiO3 buffer layer and had Tc=89 K and Jc=106 A/cm2 at 84 K. The filter showed insertion loss of 1.7 db at 77 K, and 1.5 db at 70 K, compared to 7.3 db for Au filters at 77 K. Subtracting the losses in the Au ground plane, we estimated that the superconductor surface resistance is lower than one fourth that of Au at 77 K and 55 GHz.

Energy losses accompanying the detachment of an electron from Cl− in collision with H2 and D2 have been measured using a time‐of‐flight technique. Four different energy loss channels are identified and their excitation functions mapped: (1) ΔE?4 eV corresponding to ’’simple detachment’’ (E.A. Cl−=3.6 eV); (2) ΔE?8 eV corresponding to dissociative attachment; (3) ΔE ranging from 11 eV at Erel?15 eV to 14 eV at Erel?50 eV associated with detachment to the 2Σ+g state of H−2; (4) ’’spectator’’ backscattering from a single hydrogen atom.

We have utilized the time‐of‐flight (TOF) technique to measure the energy loss of Cl− ions backscattered from H2 in the relative energy region of 4 to 11 eV. For relative energy less than 7 eV, this collision yields vibrational excitation of the H2 molecule and the amount of energy transferred is similar to that in the isoelectronic analog, i.e., K+–H2. In the case of K+, the results were in good agreement with an exact classical calculation involving only the particle masses, the K+–H2 repulsion, and the H2 potential. At higher relative energy (Erel≳7 eV), however, the process is much more inelastic with a minimum energy loss of greater than 4 eV, corresponding to dissociation of the H2 molecules. The threshold for dissociation observed here is more commensurate with that predicted for a strong [H2Cl]− surface than with simple T–V transfer kinetics.

Far‐infrared magnetotransmission experiments were carried out on two Hg1−xCdxTe superlattices with graded composition grown by laser molecular beam epitaxy. A superlattice k⋅p model was used to calculate the subband structures of the superlattices. Good agreement is found between the experimental results and the theory if the valence‐band offset is assumed to be small.

This letter reports the achievement of a high‐performance, broad‐spectral‐band infrared detector with the InAs1−xSbx alloy system using a backside‐illuminated heterostructure approach. The basic structure of the detector is obtained with InAs1−xSbx grown by a liquid phase epitaxy technique on a GaSb substrate under lattice‐matched or nearly lattice‐matched conditions. The measured photoresponse covers the spectral range 1.7–4.2 μm with an external quantum efficiency of 65% without antireflective coating. The typical zero‐bias resistance area product is in excess of 109 Ω cm2. The typical leakage current desity is less than 10−9 A/cm2 for 100 mV reverse bias. All parameters were measured at 77 K.

The heteroepitaxial growth of (111) CdTe on (100) GaAs substrates has been obtained by laser assisted deposition at 350 °C. Films 5–14 μm thick were characterized by x‐ray diffraction, UV reflectance measurement, and transmission electron microscopy. Results indicate good crystallinity with 105 cm−2 dislocation densities beyond a few microns from the CdTe/GaAs interface.

Properties of n (AlxGa1−xAs) ‐p (GaAs) heterojunctions grown by liquid‐phase epitaxial (LPE) techniques were investigated. It was found that an energy barrier in the form of a ’’spike’’ can be formed at the interface as a result of Zn out diffusion from the GaAs layer. When Ge was substituted for Zn as the p‐type dopant, no such energy barrier was observed. The results are interpreted in terms of the graded‐gap heterojunction model.

An n‐channel metal‐insulator‐semiconductor charge‐coupled device has been successfully demonstrated in p‐type epitaxial Hg0.7Cd0.3Te (λco≃5.0 μm, 77 K) grown by liquid‐phase epitaxy on CdTe substrate. A three‐bit, three‐phase device was operated at 77 K, yielding a charge transfer efficiency greater than 0.995 between 5 and 50 kHz clock frequencies. Ion‐implanted n+/p diodes facilitated signal input and direct output signal detection.

Laser molecular beam epitaxy offers instantaneous and accurate composition and thickness control that was used successfully to grow HgCdTe‐based superlattice structures with rectangular, trapezoidal, triangular, and sawtooth‐shaped quantum wells. Their structures were characterized with cross‐sectional transmission electron microscopy and low‐temperature Auger depth profiling.

Planar infrared photodiodes have been fabricated on Hg1−xCdxTe (x=0.22) epitaxial layers which were grown on CdTe substrates by the liquid phase epitaxy technique. The n+‐p junctions were formed by ion implantation. The R0A products of the diodes have been measured to be ∼105 Ω cm2 at 40 K and ∼107 Ω cm2 at 20 K. These R0A values are believed to be the highest ever reported for HgCdTe photodiodes with comparable cutoff wavelengths. It was found that between 77 and 40 K the diode R0A was limited by generation‐recombination current. Effects of field plate bias on diode properties were also analyzed.

High‐performance backside‐illuminated photodiodes have been fabricated for the first time from InAs1−xSbx‐InAs heterostructures prepared by liquid‐phase‐epitaxy technique. The peak wavelength can be tuned compositionally from 3.1 to over 7.0 μm at 77 K. The half‐width of the spectral responses as narrow as 1760 A (at 4.0 μm) have been achieved. Internal quantum efficiencies of 90% and zero‐bias‐resistance–area products of 2×107 Ω cm2 have been obtained at 77 K.

A planar HgCdTe/CdTe avalanche photodiode with peak responsivity at 1.22 μm and cutoff at 1.25 μm has been fabricated successfully by liquid phase epitaxy (LPE). Avalanche gains of higher than 15 have been obtained with 1.06‐μm Nd:yttrium aluminum garnet (YAG) laser illumination. A reverse breakdown voltage of 80 V and a leakage current density of 1×10−4 A/cm2 at 40 V were measured. The peak quantum efficiency at 1.22 μm is 72% without any antireflection coating.

Millimeter‐wave power is generated from an n+/p Hg0.74Cd0.26Te photovoltaic diode illuminated by two CO lasers of 5.467‐ and 5.478‐μm wavelengths, respectively. The output frequency is determined by the laser line separation to be 110 GHz. A maximum power of 0.75 μW is observed when the diode is dc biased at 0.5 V in the reverse direction.

Very high surface temperature can be reached by exposing CdTe to intense laser radiation. Under this condition, the evaporation is dissociative to form a mixture of Cd, Te, and Te2. The fraction of atomic Te can be varied by changing the laser power, thus allowing a systematic elucidation on the role of atomic Te in the growth kinetics of (111) CdTe homoepitaxy. In comparison with Te molecules, the use of Te atoms improves the surface morphology of layers grown on the (111)A face and enhances the growth rate on both the (111)A and (111)B faces. Results suggest that the atomic Te is more reactive.

Te precipitates in CdTe have been characterized by Auger spectroscopy, x‐ray diffraction, and Raman spectroscopy. The x‐ray results show that the precipitated Te in Bridgman‐grown CeTe crystals has the same structural phase as observed in elemental Te under high pressure. Auger and Raman microprobe spectroscopy were carried out to confirm Te precipitates in CdTe and identify the symmetry of the Te precipitates.

Steps in optical absorption spectra due to transitions to different subbands have been observed in HgCdTe‐based nonrectangular superlattices. The sawtooth‐shaped superlattice band gap shows much less thermal degradation than the conventional rectangular superlattice. The improved thermal stability can be attributed to the enhanced quantization effect in which the dependence of superlattice band gap on quantum well size is less sensitive for a sawtooth quantum well than for a rectangular quantum well.

Hg1−xCdxTe epilayers with a wavelength of ∼1.33 μm have been successfully grown by liquid phase epitaxy. Photodiodes were fabricated and measured. Analysis of the heterojunctions indicates that at room temperature the junction current at forward bias is dominated by a generation‐recombination mechanism. The generation‐recombination effective lifetime was estimated to be 2×10−7 s. A leakage current density of 9×10−6 A/cm−2 was observed at a reverse bias of 30 V, and the diode breakdown voltage was 70 V.

High‐performance HgCdTe photodiodes have been formed by successive growth of p‐ and n‐type epitaxial layers on CdTe substrates via the liquid phase epitaxy technique. These diodes exhibit high resistance‐area (R0 A) products at high temperatures: R0 A products of 1 and 30 Ω cm2 have been observed at 283 and 200 K, respectively, for Hg0.68Cd0.32Te (λco=4.0 μm at 200 K). The saturation current density for the grown junction photodiode at 300 K is 0.12 A/cm2.

The principles of superinjection are elucidated through an analysis of the injection properties of p (GaAs) ‐p (AlGaAs) ‐n (AlGaAs) heterostructure devices. It is shown that under forward bias, the quasi‐Fermi level is discontinuous at the heterojunction interface. The threshold currents above which superinjection takes place for different device parameters are calculated. The results are useful in designing heterojunction lasers and related devices.