New approach to the design of Schottky barrier diodes for THz mixers

Near-ideal GaAs Schottky barrier diodes especially designed for mixing applications in the THz frequency range are presented. A diode fabrication process for submicron diodes with near-ideal electrical and noise characteristics is described. This process is based on the electrolytic pulse etching of GaAs in combination with an in-situ platinum plating for the formation of the Schottky contacts. Schottky barrier diodes with a diameter of 1 micron fabricated by the process have already shown excellent results in a 650 GHz waveguide mixer at room temperature. A conversion loss of 7.5 dB and a mixer noise temperature of less than 2000 K have been obtained at an intermediate frequency of 4 GHz. The optimization of the diode structure and the technology was possible due to the development of a generalized Schottky barrier diode model which is valid also at high current densities. The common diode design and optimization is discussed on the basis of the classical theory. However, the conventional fomulas are valid only in a limited forward bias range corresponding to currents much smaller than the operating currents under submillimeter mixing conditions. The generalized new model takes into account not only the phenomena occurring at the junction such as current dependent recombination and drift/diffusion velocities, but also mobility and electron temperature variations in the undepleted epi-layer. Calculated diode I/V and noise characteristics are in excellent agreement with the measured values. Thus, the model offers the possibility of optimizing the diode structure and predicting the diode performance under mixing conditions at THz frequencies

Submillimeter satellite radiometer Final engineering report

All solid-state superheterodyne Dicke radiometer for submillimeter wavelength

Submillimeter satellite radiometer first semiannual engineering progress report

Development of 560 GHz fourth harmonic mixer and 140 GHz third harmonic generator for use in radiomete

Infrared receivers for low background astronomy: Incoherent detectors and coherent devices from one micrometer to one millimeter

The status of incoherent detectors and coherent receivers over the infrared wavelength range from one micrometer to one millimeter is described. General principles of infrared receivers are included, and photon detectors, bolometers, coherent receivers, and important supporting technologies are discussed, with emphasis on their suitability for low background astronomical applications. Broad recommendations are presented and specific opportunities are identified for development of improved devices

Plasmonic Rectenna for Efficient Conversion of Light into Electricity

Medical genetic

Microwave device investigations Semiannual progress report, 1 Oct. 1969 - 1 Apr. 1970

Beam-plasma interactions, cyclotron harmonic instability study, and millimeter and submillimeter wave detection by paramagnetic material

Recent advances in solid-state organic lasers

Organic solid-state lasers are reviewed, with a special emphasis on works published during the last decade. Referring originally to dyes in solid-state polymeric matrices, organic lasers also include the rich family of organic semiconductors, paced by the rapid development of organic light emitting diodes. Organic lasers are broadly tunable coherent sources are potentially compact, convenient and manufactured at low-costs. In this review, we describe the basic photophysics of the materials used as gain media in organic lasers with a specific look at the distinctive feature of dyes and semiconductors. We also outline the laser architectures used in state-of-the-art organic lasers and the performances of these devices with regard to output power, lifetime, and beam quality. A survey of the recent trends in the field is given, highlighting the latest developments in terms of wavelength coverage, wavelength agility, efficiency and compactness, or towards integrated low-cost sources, with a special focus on the great challenges remaining for achieving direct electrical pumping. Finally, we discuss the very recent demonstration of new kinds of organic lasers based on polaritons or surface plasmons, which open new and very promising routes in the field of organic nanophotonics

Density of gap states in hydrogenated amorphous silicon

Amorphous silicon hydride films have been grown by an improved r.f. sputtering method in a hydrogen-argon atmosphere. Deposition parameters such as substrate temperature, gas flow rate, r.f. power, and argon partial pressure were kept constant, while hydrogen partial pressure was varied. The infrared vibrational modes, optical absorption, conductivity, and density of gap states from the Fermi level upward toward the conduction band edge of these films have been studied as a function of hydrogen content of the films. The density of states distribution of the films has been deduced from Space Charge Limited Current measurements with an Au/a-Si:H Schottky diode structure. Samples with (\u27(TURN)) 15.5% at. H have densities of states of 3 x 10(\u2714) states/cm(\u273) eV and show large majority carrier mobility-lifetime products of 10(\u27-5) cm(\u272)V(\u27-1). An Au/a-Si:H diode which is nearly ideal (diode quality factor = 1.05) was obtained for a-Si:H films with hydrogen concentrations of about 16 at. %. The experi- mental results indicate that a high quality a-Si:H material with a low;density of states of 3 x 10(\u2714) states/cm(\u273)eV can be obtained by r.f. sputtering method; (\u271)DOE Report IS-T-1163. This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy