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Micro-electrochemical machining (micro-ECM) has been widely used for microscale and nanoscale processing of materials. The performance of the nanosecond pulse power supply is directly related to the precision of micro-ECM, which is one of the core technologies for micro-ECM. In this work, a nanosecond pulse power supply, with adjustable pulse frequency, duty cycle, and voltage, was designed with an STM32F103VET6 single-chip microcomputer as the control core and a metal-oxide-semiconductor field-effect transistor as the chopper switch component. The performance test has shown that the power supply can produce a continuous pulse with the highest frequency of 8 MHz, the shortest pulse width of 50 ns, the maximum peak current of 12 A, and the maximum voltage of 10 V. As compared with the power supply reported in the literature, the present power supply demonstrated the enhanced output current and improved waveform of the nanosecond pulse output, which could result in better machining accuracy and efficiency for micro-ECM.

By applying density functional theory combined with nonequilibrium Green’s function, we investigate the electronic and transport properties of V-doped zigzag phosphorene nanoribbons (ZPNRs) with different edge passivations. The results show that the electronic and transport properties of vanadium-doped ZPNRs (V-ZPNRs) can be tuned by the edge passivation types. V-ZPNRs passivated by sulfur atoms possess stronger conductivity than bared ones, and edge passivation by hydrogen and halogen (F and Cl) atoms can transform V-ZPNRs from magnetic metals to magnetic semiconductors. Moreover, due to the edge passivation by hydrogen and halogen atoms, V-ZPNRs exhibit dual spin polarizability and negative differential resistance effects. The findings provide theoretical support in modulating the electronic transport properties of ZPNRs, which may be useful in designing phosphorene-based spintronic devices.

By using a thin 13C diamond chip together with a 12C diamond chip as sensors, the diamond Raman spectra provide the means to measure pressure precisely (±0.3 GPa) at any temperature (10–1200 K) and simultaneous hydrostatic (or quasihydrostatic) pressure (0–25 GPa) for any sample compatible with an externally heated diamond-anvil cell. Minimum interference between the Raman spectrum from the diamond anvils and those of the pressure sensors is obtained by measuring pressures with the Raman signal from the 13C diamond chip up to 13 GPa, and that from the 12C chip above 10 GPa. The best crystallographic orientation of the diamond anvils is with the [100] direction along the direction of applied force, in order to further minimize the interference. At 298 K, the pressure dependence of the 13C diamond first-order Raman line is given by ν(P)=νRT+aP for 91 at. % 13C diamond, where νRT(13C)=1287.79±0.28 cm−1 and a(13C)=2.83±0.05 cm−1/GPa. Analysis of values from the literature shows that the pressure dependence of...

Mutilayered thin (Ba0.80Sr0.20)(Ti1−xZrx)O3 (BSTZ) films with various compositional graded layers (CGL) have been successfully fabricated on Nb doped SrTiO3 substrates by pulsed-laser deposition technique with four BSTZ ceramic targets (x=0.36,0.18,0.08,0). The gradients of compositions are artificially tailored in multilayered thin films by varying the CGL, and x-ray diffraction indicates that the internal stress is modulated in the multilayered films. Influence of the composition gradient on the dielectric properties has been investigated at the temperature range from 120 to 440K. Temperature stability of permittivity of the multilayered films is found to be improved with the increase of the gradients of compositions. Moreover, a dielectric relaxation process with activation energy of 1.02eV is observed, which is also related to the composition gradient, and can be described to motion of oxygen vacancies. The results show that the temperature stability of permittivity can be tailed by the design of mult...

Effect of Co doping on leakage current has been investigated in capacitor consisting of Ba0.5Sr0.5Ti1−xCoxO3 (BSTC, x=0, 0.002, 0.010) thin film, Pt top electrode, and Nb-doped SrTiO3 (STON) bottom electrode. Co doping remarkably decreases the leakage current in BSTC thin film, such as from 9×10−7 A in undoped thin film to 8×10−11 A in 1.0 at. % Co-doped BSTC thin film at bias voltage of 6 V. In the case of the Pt electrode positively biased, the leakage current shows space-charge-limited-current behavior. The trap-filled-limit voltage and the calculated trapped electron density increase with Co concentration in BSTC thin film. The mechanism of the reduction of the leakage current by Co doping is discussed.

Multilayered thin films of (Ba0.80Sr0.20)(Ti1−xZrx)O3 (BSTZ) with compositionally graded layer (CGL) have been fabricated by pulsed laser deposition on Pt/TiO2/SiO2/Si substrate. In each CGL, four individual layers of BSTZ with x=0.36, 0.18, 0.08 and 0 are grown in series with equal thickness. Three kinds of thin-film CGL samples comprising one, two or four CGLs have been elaborated with the final same thickness, and the thickness of each CGL is accordingly varied in different samples to achieve the gradients of composition. The crystalline structures of the CGL thin films are successively characterized using x-ray diffraction and their electrical properties such as ac dielectric properties and polarizations are investigated. Improved dielectric properties and tunability of permittivity have been observed in the multilayered CGL films compared to single-layer BSTZ films prepared in the identical condition. Furthermore, with increasing gradients of compositions in the CGL multilayered films, the dielectric...

Crystal structure and magnetic properties of the NdCo9.5-xFexV2.5 compounds with x=0-3.5 have been investigated. The lattice parameters increase linearly with the Fe content and the Curie temperature increases substantially at small amount of Fe content and then gradually with the further increase of x. A domain-wall pinning phenomenon was observed in all of the compounds and becomes less obvious as x increases. At a higher field, the compounds exhibit a field-induced metamagnetic transition. The critical field for the metamagnetic transition increases first then decreases with the Fe content, whereas the difference of the magnetization between 14 and 5 T increases with x. The observation can be understood by considering an interplay of the volume expansion, enhanced exchange coupling parameter J(RT) and the T sublattice moment mu(T) due to the Fe substitution for Co. (C) 2004 American Institute of Physics.

Reshaping effects of ns pulses were theoretically and experimentally investigated using bulk CdTe. The experiments were performed using a 1.064 μm Nd:YAG laser with pulse duration of 10 ns. We observed that the laser pulses emerging from the sample experienced temporal compression and modulation which were found to be dependent on the input irradiance, the distance from the exit surface of the sample, and the cross sectional area detected. Self‐defocusing and the formation of ring structures were also observed in the transmitted spatial profile and were found to be dependent on the input irradiance and the position of the detector from the sample. In our model we assumed that the free carriers generated by the two‐photon absorption process were responsible for the induced nonlinear change in the index of refraction. As a result, the temporally and radially dependent phase shift encoded to the field that emerged from the sample was the cause of the reshaping effect. The results of our model, for both the spatial and the temporal profiles, are in good agreement with the experimental results. Moreover, the nonlinear parameters deduced from the fitting are in good agreement with previous experimental and theoretical results.

A series of Pb(Zr,Ti)O3 (PZT) films with tetragonal/rhombohedral multilayered structures has been grown on Pt/TiO2/SiO2/Si substrates by rf magnetron sputtering at a relative low temperature. All the films comprise 12 periodicities of Pb(Zr20Ti80)O3/Pb(Zr80Ti20)O3 in constant thickness of 40 nm, but the layer thicknesses of tetragonal phase (dT) and rhombohedral phase (dR) in one periodicity are varied. The electric properties of the films are investigated as a function of dT/dR from 10/30 to 35/5. An enhanced dielectric property is observed in the multilayered films. Especially, a optimal value of dT/dR=30/10 is obtained, where the dielectric constant reaches maximum value of 469 at 100 kHz with a loss tangent of 0.037, and the dielectric constant is about five times that of the single tetragonal phase PZT film formed under the identical condition. Moreover, the polarization also increases in the multilayered films, and remarkably, the film of 30/10 exhibits larger remanent polarization, lower coercive voltage, and more symmetric hysteresis than the other films. The enhancement of dielectric properties is attributed to the presence of interfaces between the tetragonal and the rhombohedral phase layer. This study suggests that the design of the multilayered PZT film capacitor with tetragonal and rhombohedral phase should be an effective way to enhance the dielectric and ferroelectric performance in devices.

A Raman system is described which is suitable for rapid determination of Raman spectra of silicates and other weak Raman scatterers under simultaneous high‐pressure and high‐ temperature conditions. Samples are pressurized with an argon pressure medium and Sm:YAG pressure standard in an Inconel 718 or rhenium Merrill–Bassett diamond–anvil cell that is externally heated in a vacuum oven equipped with quartz windows on either side. Raman spectra are excited and collected through the front window using ≊160° scattering geometry. A triple spectrometer in conjunction with a holographic notch filter, disperses the Raman scattered radiation onto a liquid‐nitrogen‐cooled CCD detector. Simultaneously measured Sm:YAG fluorescence spectra are collected through the rear window and routed via an optical fiber to a second multichannel spectrometer system equipped with a diode‐array detector. The high sensitivity of the detectors and the simultaneous measurement technique enable detection of and compensation of pressure...

In this article we report the first detailed study of electrochemical capacitance‐voltage profiling of ZnSe. An electrolyte consisting of 1 M sodium hydroxide and 1 M sodium sulphite has been developed that does not deposit selenium while etching the surface of n‐type ZnSe during C‐V profiling. The dissolution number of the electrolyte/ZnSe system is a function of the strength of electrolyte and the etching current and in order to obtain an accurate etching depth a constant etching current mode was used. A wide range of doping concentrations including both uniformly doped and staircase structures have been measured demonstrating that the electrochemical C‐V profiler can now be a routine tool for assessing the growth parameters of ZnSe.

To improve the accuracy in the calculation of dynamic contact angle for drops on the inclined surface, a significant number of numerical drop profiles on the inclined surface with different inclination angles, drop volumes, and contact angles are generated based on the finite difference method, a least-squares ellipse-fitting algorithm is used to calculate the dynamic contact angle. The influences of the above three factors are systematically investigated. The results reveal that the dynamic contact angle errors, including the errors of the left and right contact angles, evaluated by the ellipse-fitting algorithm tend to increase with inclination angle/drop volume/contact angle. If the drop volume and the solid substrate are fixed, the errors of the left and right contact angles increase with inclination angle. After performing a tremendous amount of computation, the critical dimensionless drop volumes corresponding to the critical contact angle error are obtained. Based on the values of the critical volumes, a highly accurate dynamic contact angle algorithm is proposed and fully validated. Within nearly the whole hydrophobicity range, it can decrease the dynamic contact angle error in the inclined plane method to less than a certain value even for different types of liquids.

The electronic structure and the magnetism of a Mn12O12 molecule at ground state have been studied by density functional theory with a local spin density approximation. We have found that the magnetic moments of Mn ions in the tetrahedron and those of Mn ions in the crown of the Mn12O12 molecule align antiferromagnetically. The average moment per Mn ion is about 3.07μB in the tetrahedron and 4.07μB in the crown. The total spin amounts to 20.0μB which is in agreement with recent experimental results. The significant difference of magnetic moments between Mn ions at two sites is attributed to the different exchange splitting of 3d orbitals. However, the charge difference between the two kinds of Mn ions is as small as 0.22 electrons. The charge density and the spin density exhibit strong directional dependence, which indicates the strong anisotropy in this molecule.

We have employed near-field scanning optical microscopy to investigate the influence of specific microstructural defects on the optical properties of thin InGaN/GaN epilayers and quantum wells. These defects are empty “pinholes” with a hexahedron cone morphology that are nucleated by threading dislocations from the GaN buffer layer. By correlating atomic force microscopy with spatially and spectrally resolved photoluminescence (PL) on a 100 nm spatial scale, we find that the pinholes have no clearly observable effect on the PL efficiency, at least partly due to the strong carrier localization in the InGaN nonrandom alloy.

The formation of pits in GaInN quantum wells (QWs) has been studied by atomic force microscopy and transmission electron microscopy. It is found that the pits have a hexahedron cone morphology with six sidewalls on 〈1101〉 planes and dislocations connected to their vertexes. The dislocations may induce the formation of pits during the growth of GaInN QWs.

Quantum confined Stark effect p‐i‐n waveguide modulators, grown on GaAs substrates by molecular beam epitaxy and using an undoped ZnSe/ZnCdSe multiquantum well structure as the guiding layer, have exhibited intensity modulation at wavelengths of 496 and 501 nm with extinction ratios of 6 and 4, respectively. These same devices have also demonstrated a transverse linear electro‐optic effect observed as a superimposed secondary effect on the lateral intensity modulation at 514 nm in the form of phase modulation in the output of the same device. Intensity modulation has also been observed in quaternary laser waveguide structures, indicating that this is a device structure which is suitable for monolithic integration.

This letter reports the growth and characterization of ZnSe:N layers by atomic layer epitaxy (ALE) using a nitrogen rf‐plasma source. The ALE‐grown ZnSe:N layers have been investigated in terms of in situ reflection high electron energy diffraction and ex situ capacitance–voltage profiling and photoluminescence spectroscopy. The net acceptor concentration in the ALE‐grown layer has been obtained as high as 1.2×1018 cm−3 and the ALE layers of ZnSe:N show reduced number of compensating deep centers compared with the ZnSe:N grown by molecular beam epitaxy. The effects of the Fermi level at a growing surface on the generation of compensating donors with a binding energy of 57 meV are also discussed.

The compensating acceptors and donors in nitrogen δ‐doped ZnSe epilayers grown by molecular beam epitaxy using a nitrogen rf‐plasma source are studied by means of photoluminescence (PL) and photoluminescence excitation spectroscopy (PLE). The temperature dependence of PL and PLE spectra obtained from the nitrogen δ‐doped layers is investigated in detail, and a deep acceptor and a deep donor with ionization energies of ∼170 and ∼88 meV are reported for the nitrogen δ‐doped layers. These two deep centers are assigned to N clusters, i.e., NSe‐Zn‐NSe for the deep acceptor and NSe‐NZn for the deep donor.

Optical bistability at room temperature has been observed for the first time in a II‐VI semiconductor self‐electro‐optic effect device fabricated by molecular beam epitaxy. The optical switch is based on a ZnSe/ZnCdSe multiple quantum well structure situated within a p‐n junction and the devices operate at 488 nm in the blue‐green spectral region.

We report novel measurements of the room temperature refractive optical nonlinearities in a molecular beam epitaxy‐grown ZnSe epilayer at frequencies near to the band edge. Time‐resolved changes in the transmission spectrum due to a two‐photon generated plasma of free carriers are monitored with a broad‐band white‐light continuum probe. The refractive index changes, measured for photon energies between 0.8 and 0.05 eV below the free‐exciton line at 2.68 eV, with photoexcited carrier densities of (2–5)×1018 cm−3, are found to be in good agreement with a many‐body plasma calculation.

Carrier recombination processes in thin‐film epitaxial ZnSe are investigated using a transient‐grating technique. For photoexcitation levels in the 1017–1018 cm−3 range the dominant recombination mechanism is found to be radiative, described by a rate coefficient of 8×10−9 cm3 s−1. For densities exceeding approximately 2×1018 cm−3 ultrafast grating recovery is observed, accompanied by line narrowing of the near‐band‐edge blue photoluminescence; this is interpreted as being due to stimulated radiative recombination.

We report room temperature operation of a II‐VI p‐i‐n quantum confined Stark effect modulator using a ZnSe‐Zn0.8Cd0.2Se multiple quantum well structure within a ZdSe p‐n junction. A n‐type ZnSe layer was used as a novel contact to the p‐type ZnSe. Results are given for photovoltage spectroscopy, absorption, and differential absorption as a function of the applied electric field.

We have examined the compensation processes in nitrogen doped ZnSe grown by molecular beam epitaxy. Two independent donor–acceptor pair emission processes have been observed in photoassisted grown layers and detailed temperature dependence measurements have allowed us to conclude that a deep compensation donor with a binding energy of 44 meV exists in more heavily doped material. We propose that the compensating donor is a complex involving a native defect such as the (VSe‐Zn‐NSe) single donor and this suggestion is supported by the observation of changes in the carrier concentration profile with time.

Laser diode structures have been fabricated using molecular beam epitaxy with iodine from an electrochemical source for the n‐type doping and nitrogen from a plasma source for the p‐type doping. CV profiling using electrochemical etching shows uniform p doping of 4×1017 cm−3 and n doping of 1×1018 cm−3. Under pulsed current excitation blue emission at 470 nm is observed at room temperature which increases in intensity at liquid helium temperatures. Above a current density threshold of 50 A cm−2 stimulated emission is observed between 448–473 nm with a complicated mode structure.

We report the use of electrochemical capacitance‐voltage profiling of n‐type ZnSe layers by the use of NaOH electrolyte. Samples with both uniform and staircase doping profiles have been measured with concentrations ranging over 1016–1019 cm−3. The profiling technique has revealed in some samples regions of lower carrier concentration at the surface and at the ZnSe/GaAs interface. Our results demonstrate that this powerful technique can now be used for assessing the growth parameters of wideband gap II‐VI materials in the same way that is widely accepted for III‐V semiconductors.

In this work, the band alignment, interface, and electrical characteristics of HfO2/InSb metal-oxide-semiconductor structure have been investigated. By using x-ray photoelectron spectroscopy analysis, the conduction band offset of 1.78 ± 0.1 eV and valence band offset of 3.35 ± 0.1 eV have been extracted. The transmission electron microscopy analysis has shown that HfO2 layer would be a good diffusion barrier for InSb. As a result, 1 nm equivalent-oxide-thickness in the 4 nm HfO2/InSb structure has been demonstrated with unpinning Fermi level and low leakage current of 10−4 A/cm−2. The Dit value of smaller than 1012 eV−1cm−2 has been obtained using conduction method.

The emitter size effect of a series InGaAsSb base series of InP/InGaAsSb/InGaAs heterojunction bipolar transistors (HBTs) with different emitter sizes is investigated. Compared to the InGaAs base HBTs, these devices exhibit much lower base surface recombination current. This is attributed to the surface Fermi level pinning near the valence band of the antimonide base. The effect of Sb composition and doping concentration of the base on the surface recombination current is well explained by the postulate.

The effects of cobalt doping on the electrical conductivity of La0.1Bi0.9Fe1−xCoxO3 (LBFCO, x = 0, 0.01, 0.03) ceramics were investigated. It is found that the leakage current increases with cobalt dopant concentration in LBFCO. On the application of bias voltage LBFCO ceramics with cobalt doping exhibits resistive switching effects at room temperature and threshold switching effects at elevated temperatures (50 °C and 80 °C). X-ray photoelectron spectroscopy of LBFCO ceramics show that cobalt dopant is bivalent as an acceptor, which induces an enhancement of oxygen vacancy concentration in LBFCO ceramics. Possible mechanisms for both resistive switching and threshold switching effects are discussed on the basis of the interplay of bound ferroelectric charges and mobile charged defects.

Multiferroic La0.1Bi0.9FeO3 (LBFO) ceramics with high resistivity were synthesized by using a modified rapid thermal process. The LBFO ceramics show very low leakage and low dielectric loss. Well saturated ferroelectric hysteresis loops and polarization switching currents have been observed. For a maximum applied electric field of 145 kV/cm, the remanent polarization is 17.8 μC/cm2 and the coercive filed is 75 kV/cm. The dominant conduction mechanism in the LBFO ceramics has been found to be the space-charge-limited current mechanism rather than the thermal excitation mechanism. Electrical reliability related to the fatigue and polarization retention of the LBFO ceramics has also been discussed with the leakage mechanisms.

We investigate the thermal stability of pseudomorphically strained Si:C layer using high resolution x-ray diffraction (HRXRD) and Fourier transform infrared (FTIR) spectroscopy. Far below β-SiC precipitation threshold, almost complete strain relaxation is found without significant substitutional carbon (Csub) loss. FTIR shows the strain relaxation is related to volume compensation by Csub-interstitial complex formation through oxidation injection of interstitial. By multilayer HRXRD kinematical simulation, we find correlation of the enhanced strain relaxation to P distribution, implying P’s role as additional interstitial promoter during postannealing treatment. We relate our findings to recent reports on strain relaxation issues in Si:C devices fabrication.

A technology to reduce the dislocation density in GaN thin films by lateral overgrowth from trenches (LOFT) is reported. In LOFT, a GaN thin film was grown on sapphire substrate first, then trenches were formed into the thin film by etching. GaN material was regrown laterally from the trench sidewalls to form a continuous thin film. The average surface density of threading dislocations is reduced from 8×109/cm2 in the first GaN thin film to 6×107/cm2 in the regrown GaN thin film.

Self-assembled In0.22Ga0.78As quantum dots (QDs) grown on Si substrate with Ge∕SiGe as buffer layer grown by metal organic vapor phase epitaxy were investigated. Transmission electron microscopy and atomic force microscopy images were used to observe the size and space distribution of the In0.22Ga0.78As QDs grown on the GaAs∕Ge∕GeSi∕Si layer structure. The influence of the growth temperature on the QDs size and density distribution was investigated. For QDs grown at 450°C, the density of the In0.22Ga0.78As dots was estimated to be 1×1011cm−2 and the In0.22Ga0.78As QDs thickness was 5 ML (monolayer) thick.

Our previous study revealed that setting the induced intrinsic anisotropy orthogonal to the shape anisotropy to the toggle-MRAM (toggle mode magnetoresistive random access memory) element, thus giving zero total anisotropy, can reduce the operating field substantially with a greater margin. It has been confirmed that further reduction of the operating field is possible by applying a bias field keeping a substantial operating field margin, and that by choosing a proper bias field and the coupling field between the two magnetic layers composing a synthetic antiferromagnet memory element, the “orthogonal anisotropy” toggle-MRAM can be endowed with a greater margin than the conventional Stoner-Wohlfarth-type MRAM for the same strength of operating field, memory life, and half-select disturb robustness.

Ba0.5Sr0.5TiO3 (BST) thin films are among the best-known ferroelectric and dielectric materials. Ce-doped BST films have been fabricated by pulsed laser deposition in order to enhance their dielectric properties. X-ray diffraction, atomic force microscopy, and Raman spectroscopy have been used to study variations of crystal structure, surface morphologies, and phase stability of Ce-doped BST films, respectively. A strong influence of Ce doping on the properties of the BST films has been observed. First, a small amount of Ce dopant makes easy epitaxial growth of a BST film with a smooth surface on a MgO substrate. Second, residual stress in a BST film on a MgO substrate can be reduced by Ce doping, as demonstrated by the blueshift of phonon peaks in Raman spectroscopy.

Si–Ba0.5Sr0.5TiO3 composite thin films were deposited by pulsed laser deposition technique on (100) Nb:SrTiO3 substrates. The crystal structure and surface morphology of the thin films have been characterized by x-ray diffraction and atomic force microscopy, respectively. Experimental results suggested that the Si composition has played a positive role in improving the dielectric properties of the thin films. With the increased Si concentration, the dielectric loss was significantly reduced, accompanied with a tolerable reduction of tunability. In particular, the 14% Si composite film exhibited a dielectric loss of 0.005, which is much lower than that of the undoped Ba0.5Sr0.5TiO3 (BST) film. Moreover, a proper concentration of Si in the film improved the figure of merit from 9 of the undoped BST to 23 of 1.4% Si composite films.

Magnetization response to in-plane applied fields has been studied, using Stoner-Wohlfarth model, on the bilayer systems of synthetic antiferromagnet having an anisotropy configuration in which the induced intrinsic uniaxial anisotropy is set either parallel or orthogonal to the shape anisotropy. It has been found that the toggle-mode magnetoresistance random access memory operation is possible even when the shape anisotropy exceeds the intrinsic anisotropy to some extent due to the anisotropic effect of the magnetostatic coupling and that the minimum operating field and maximum relative operating field margin are attained when the two anisotropy compensate each other. The optimal operating fields increase with the increase of the absolute value of the total anisotropy constant. However, the tolerance of total anisotropy constant in the positive direction is greater than in the negative direction if zero total anisotropy is chosen to be optimal.

The magnetization behavior of generalized synthetic antiferromagnet (SAF) is investigated by analytic/numeric method, applying Stoner–Wohlfarth model to each layer. Critical conditions for toggle-mode switching are given using the critical-field curves obtained from the field trajectories giving a constant value to the average angle of the magnetizations of the two layers or to the angle between the two, leaving the other variable. The critical fields for the toggle operation are found to be expressed by analytical formulas including only controllable element parameters, facilitating the parameter optimization for the memory element. The results obtained for the generalized SAF are useful in determining the tolerance for the parameter imbalance. Half-select disturb effect is still one of the important issues to be taken into account in designing the memory element.

We report a 1.3‐μm GaAs traveling‐wave electro‐optic waveguide modulator with a 3‐dB optical bandwidth in excess of 20 GHz. The bandwidth was determined by directly detecting the modulated optical signal with a high‐speed InP/GaInAs photodiode. The modulator has a coplanar strip electrode configuration with a double heterojunction Al0.032Ga0.968As/GaAs/Al0.032Ga0.968As optical guide grown by low‐pressure organometallic vapor phase epitaxy.

Enhanced optically induced voltages have been observed across the junction of metal‐barrier‐metal point‐contact diodes which exhibit a current‐controlled negative differential resistance. Responsivities in excess of 5 V/W have been demonstrated when the incident optical beam is focused to ∼1 W/cm2 at the junction. This enhancement is in agreement with the behavior expected from the rectification of the optical field.

This letter describes a new nondestructive measurement technique—cw electro‐optic probing, and reports results of experiments on GaAs coplanar waveguide sample. The technique is simple in instrumentation and convenient in applications. We believe that it can become a powerful tool for studying the electric field in various devices and integrated circuits.

Up to 20 dB of photocurrent amplification with a frequency response of 2 GHz has been observed in GaAs Schottky photodiodes. The amplification may be caused by a reduction in Schottky built‐in potential under illumination. The device may find application in improving the sensitivity of optical receivers.