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Millimeter-wave frequency converters on a diode with a Schottky barrier were analyzed. The analysis includes investigation of the effect of the variable capacitance of the diode's elements on the frequency converters. Specifically, the transmission, impedance, and noise characteristics of the frequency converters were examined.
A power conditioner was developed which used a capacitor diode voltage multiplier to provide a high voltage without the use of a step-up transformer. The power conditioner delivered 1200 Vdc at 100 watts and was operated from a 120 Vdc line. The efficiency was in excess of 90 percent. The component weight was 197 grams. A modified boost-add circuit was used for the regulation. A short circuit protection circuit was used which turns off the drive circuit upon a fault condition, and recovers within 5 ms after removal of the short. High energy density polysulfone capacitors and high speed diodes were used in the multiplier circuit.
High resolution spectra in the region of the 2-nu9 band of nitric acid have been obtained for selected portions of the HNO3 spectrum using tunable diode laser techniques. Continuous spectra are presented from 891.25/cm to 898.77/cm, with a spectral resolution less than or equal to 0.001/cm (30 MHz). Absolute line intensities and line positions are presented. Absolute wavelength calibration was obtained by frequency mixing the diode laser with a C(13)O2(16) isotope laser. Self and foreign gas (N2) broadening coefficients were iteratively calculated from the experimental data and were determined.
Structure made by As implantation of carefully prepared high-conductivity CdS surfaces followed by Pt deposition and 450 C anneal display rectifying, although substantially different, I-V characteristics in the dark and during illumination with subband-gap light. Structures prepared in the same way on an unimplanted portion of the substrate have similar I-V characteristics, except that the forward turnover voltage for an illuminated unimplanted diode is much smaller than that for an implanted diode. It is suggested that the charge conduction in both structures is dominated by hole and/or electron tunneling through a metal-semiconductor potential barrier. The tunneling processes appear to be quite sensitive to subband-gap illumination, which causes the dramatic decreases of turnover voltages and apparent series resistances. The difference in turnover voltage appears to be caused by interface states between the Pt electrode and the implanted layer, which suggests a MIS model.
Tunable diode laser spectroscopy is used to measure the infrared vibration-rotation spectra of the ClO radical. The radical is generated in a flow system where a Cl2-He mixture passes through a microwave discharge to dissociate the Cl2. An O3-O2 mixture from an ozone generator is injected into the system downstream of the microwave discharge where O3 combines with Cl to form ClO. By adjusting the gas flow rates to yield an excess of Cl atoms, all the ozone is combined. ClO concentration is measured with UV absorption at 2577 and 2772 A and a deuterium lamp as a continuous source. Total cell pressure is 5.5 torr. The diode laser spectrometer is calibrated with ammonia lines as a reference where possible. The frequency of vibration-rotation lines is expressed as a function of rotational quantum number, fundamental vibrational frequency, and the rotational constants of the upper and lower vibrational states.
Diodes manufactured by Siemens and Motorola were tested. Testing of Motorola diodes was stopped in all 3 groups because 50% failure-rate limit was reached. Siemens lot endured more testing in groups 1 and 2 and completed testing on group 3. Failure analysis was performed for group 2 testing.
Tested diodes were manufactured by Semtech and Micro Semiconductor. Micro Semiconductor diodes experienced no failures in groups 2 and 3 testing and only four failures in group 1.
The reliability of switching diode JANTX1N5614 was tested. The effect of power/temperature step stress on the diode was determined. Control sample units were maintained for verification of the electrical parametric testing. Results are reported.
Report describes effects of power and temperature overstress on Semtech and Micro Semiconductor diodes. Semtech devices failed with excessive reverse bias leakage due to external paint. Micro Semiconductor diodes had reverse bias leakage failure due to damaged silicon.
Report describes effects of power and temperature overstress on Semtech and Micro Semiconductor devices. Only two Semtech diodes failed catastrophically. Testing on Micro Semiconductor devices stopped because failure limit was reached. Micro diodes suffered lead separation.
A tunable infrared heterodyne radiometer (TIHR) which uses a diode laser as the local oscillator is described as well as methods for the evaluation of the excess noise characteristics of the tunable diode laser. Preliminary atmospheric absorption data taken with the TIHR are presented and show the capability of the TIHR for making the highest resolution atmospheric measurements to date.
Recent developments in the technology of Pb-salt diode lasers which have led to significant improvements in reliability and lifetime, and to improved operation at very long wavelengths are described. A combination of packaging and contacting-metallurgy improvements has led to diode lasers that are stable both in terms of temperature cycling and shelf-storage time. Lasers cycled over 500 times between 77 K and 300 K have exhibited no measurable changes in either electrical contact resistance or threshold current. Utilizing metallurgical contacting process, both lasers and experimental n-type and p-type bulk materials are shown to have electrical contact resistance values that are stable for shelf storage periods well in excess of one year. Problems and experiments which have led to devices with improved performance stability are discussed. Stable device configurations achieved for material compositions yielding lasers which operate continuously at wavelengths as long as 30.3 micrometers are described.
Description of an optical pattern recognition system employing a laser-diode lensless MSF correlator based on the use of holographic optical elements (HOE). The system has size, cost, and weight advantages over conventional optical processors, and it is believed to be the first unification of MSF correlation, laser diode, and HOE technologies.
A tunable diode laser spectrometer with several unique features has been developed for use in the middle IR. The all-reflective optical system has a dual-beam configuration before the dispersive mode selector to eliminate transit-angle errors at the calibration etalon. By maintaining separated beams through the mode selector, beam combiner losses are avoided. Averaging successive sweeps of the current-modulated laser permits stable reproducible spectral integrations, eliminating etalon thermal errors and producing high photometric sensitivity. Line strengths have been measured using this instrument for eleven transitions in nu4 of (C-12)H4. These include R0 and R1 and nine P-branch transitions in the 1202-1263-per cm range. Techniques for measuring strengths with a diode laser are discussed.
The reduction of the equivalent noise temperature in liquid-nitrogen-cooled submillimeter-wave mixers by the use of Schottky barriers on InSb instead of GaAs is evaluated by an analytical model that assumes limited local oscillator power and matched impedances. The calculations, executed at 1.0 and 1.8 THz, take plasma resonance and skin effect into account. For single and multiple contacts on homogeneous semiconductor materials of optimum doping, the noise of InSb diodes is smaller than that of GaAs diodes by a factor of 3 to 14. A simplified model is used to predict the performance of epitaxial structures as well as alternative materials.
Double-injection (DI) switching devices consist of p+ and n+ contacts (for hole and electron injection, respectively), separated by a near intrinsic semiconductor region containing deep traps. Under proper conditions, these devices exhibit S-type differential negative resistance (DNR) similar to silicon-controlled rectifiers. With the added influence of a p+ gate appropriately placed between the anode (p+) and cathode (n+), the current-voltage characteristic of the device has been manipulated for the first time to exhibit a variable N-type DNR. The anode current and the anode-to-cathode voltage levels at which this N-type DNR is observed can be varied by changing the gate-to-cathode bias. In essence, the classical S-type DI diode can be electronically transformed into an N-type diode. A first-order phenomenological model is proposed for the N-type DNR.
A state of the art, tunable diode laser infrared heterodyne spectrometer was designed and constructed for ground based observations throughout the 8 to 12 micron atmospheric window. The instrument was optimized for use with presently available tunable diode lasers, and was designed as a flexible field system for use with large reflecting telescopes. The instrument was aligned and calibrated using laboratory and astronomical sources. Observations of SiO fundamental (v = 1-0) and hot band (v = 2-1) absorption features were made in sunspots near 8 microns using the spectrometer. The data permit an unambiguous determination of the temperature pressure relation in the upper layers of the umbral atmosphere, and support the sunspot model suggested by Stellmacher and Wiehr.
A comparison of measured and predicted signal-to-noise ratio is made in an optical heterodyne spectrometer utilizing a tunable diode laser which exhibited excess noise. It is shown that good agreement between predicted and measured signal-to-noise ratios results if excess noise effects due to tunable diode lasers are included in the predictions. The methods used to quantify excess noise and to incorporate their effects into predictions of signal-to-noise ratio are discussed.