We have developed multipurpose spectral technique for amplitude and phase measurements at frequencies 100–1000 GHz based on the use of backward wave oscillators (BWOs) as sources of probing radiation. It utilizes to the utmost all the remarkable advantages of BWOs such as high radiation intensity, monochromaticity, polarization, as well as high speed and wide range of frequency tuning. Extremely simple and flexible open-space measurement geometries are used. The developed technique seems to be the most appropriate and promising for the reliable, precise and mass characterization of materials and devices at millimeter-submillimeter waves.

Ceramics of Ba3.75Nd9.5Ti18O54 substituted with 2, 5, 10, 20 and 50% Sr have been prepared by the mixed oxide route. Specimens were sintered at temperatures in the range 1350–1500°C. Densities were ∼95% theoretical. The solubility limit for Sr replacing Ba was found to be ∼10%. The relative permittivity (∼80) was almost independent of Sr content, but 2% Sr increased the Qxf value to a maximum of 11000. Static simulation of Sr- bearing Ba3.75Nd9.5Ti18O54 successfully reproduced the structure and lattice parameters to within 1–2%. Different site distributions of Ba-Sr ions have been explored.

Specific advantage of millimeter (MM) wave aquametry is discussed. MM waves ensure better spatial resolution and better sensitivity to water than microwaves. MM waves are less sensitive to conducting impurities than microwaves, and MM waves can be used for water testing in media that are opaque to optical and infrared radiation. In the paper the water content measurement methods for some liquid and solid-state materials are described. Examples of devices for water control in crude oil, alcohol, powders used in metallurgy, paper, timber are considered. Usually it is possible to measure moisture content in real time (including in flow) with uncertainty less than 0.1%.

Resonance Tunneling Diodes (RTDs) are devices that can demonstrate very highspeed operation. Typically they have been fabricated using epitaxial techniques and materials not consistent with standard commercial integrated circuits. We report here the first demonstration of SiO2-Si-SiO2 RTDs. These new structures were fabricated using novel combinations of silicon integrated circuit processes.

In subsurface characterization for Si wafers using a photoconductivity technique with a ultra-violet photoexcitation and millimeter wave reflection, high sensitivity technique for100 GHz was discussed experimentally and theoretically. The technique detected photoconductivity decays measured for p/p+ and n/n+ epitaxial wafers. The epilayer contaminated with Mo and Fe was characterized by the technique. Photoconductivity amplitude (PCA) intensity measured for as-polished Si wafers in commercial use after removing the subsurface by SC1 cleanings well reflected the behavior of removal of slight subsurface damage induced by mirror-polishing. The damage depth was determined to be 21 nm.

Examples of novel solid state devices are presented, together with descriptions of their applicability to the diagnosis of laboratory, processing and fusion plasmas. GaAs varactor diodes can be arranged in large monolithic grid arrays, forming millimeter wave frequency multiplier based sources and high speed switches, or embedded in transmission lines to provide a true time delay for phased antenna array beam steering. Micro-electromechanical systems (MEMS) switches are exciting new devices with numerous applications, including low loss millimeter wave switches, phase shifters and mechanically tunable structures.

GaAs Schottky barrier diodes remain a workhorse technology for submillimeter-wave applications including radio astronomy, chemical spectroscopy, atmospheric studies, plasma diagnostics and compact range radar. This is because of the inherent speed of these devices and their ability to operate at room temperature. Although planar (flip-chip and beam-lead) diodes are replacing whisker contacted diodes throughout this frequency range, the handling and placement of such small GaAs chips limits performance and greatly increases component costs. Through the use of a novel wafer bonding process we have fabricated and tested submillimeter-wave components where the GaAs diode is integrated on a quartz substrate along with other circuit elements such as filters, probes and bias lines. This not only eliminates the cost of handling microscopically small chips, but also improves circuit performance. This is because the parasitic capacitance is reduced by the elimination of the GaAs substrate and the electrical embedding impedance seen by the diodes is more precisely controlled. Our wafer bonding process has been demonstrated through the fabrication and testing of a fundamental mixer at 585 GHz (Tmix < 1200K) and a 380 GHz subharmonically pumped mixer (Tmix < 1000K). This paper reviews the wafer bonding process and discusses how it can be used to greatly improve the performance and manufacturability of submillimeter-wave components.

Thin dielectric films on the dielectric substrate are widely employed in millimeter and submillimeter wave device applications, so the problem of precise measurement of their properties is important. One of the most accurate technique for measurement of dielectric properties is the open resonator technique.

In this work we propose the method for measurements of thin dielectric film properties on the dielectric substrate using the open semispherical resonator. A good agreement (within 1 %) was obtained in refractive index data between results obtained with direct measurements and with proposed method for thin layer of SI GaAs on a sapphire substrate.

State of the art in development of millimeter wave radiometric imaging systems is analyzed and discussed. One-dimension array of 16 radiometers with mechanical scanning of the offset parabolic antenna is experimentally demonstrated that offers rms 0.03 K at time constant 1 s and instant field of view of 4×60 mrad.

The UV/mm-wave technique composed of ultraviolet photoexcitation and millimeter wave probe was examined with photoconductivity amplitude (PCA) to characterize the slight subsurface damage induced by implanting H2+ ion into the subsurface at sub micron depth of Si wafers. The identical samples were also characterized using pulse photoconductivity amplitude (PPCA) obtained by another technique which is specified by blue laser photoexcitation and microwave probe. PCA decreased with increase of ion dose, which coincided well with the result in PPCA. PPCA decreased with increase of implantation energy as 90 to 120 keV, but PCA increased at 120keV. Both PCA and PPCA well reflected the damage at sub micron depth. PCA reflected damage in shallower depth compared to PPCA.

We have characterized subsurface damage profiles of hydrogen-ion implanted silicon wafers by using a non-contact UV/Millimeter-Wave Technique and Light Scattering Topography (LST). A subsurface damage profile that was less than one micrometer was controlled by chemical mechanical polishing after hydrogen-ion implantation. On the area with the subsurface damage, the Photoconductivity Amplitude (PCA) signals measured by the UV/Millimeter-Wave Technique drastically weakened and the haze values measured by LST increased. A clear correlation has been found between the peak depth of the subsurface damage and the haze value. The spectral analyses of the surface images obtained by Atomic Force Microscopy (AFM) were carried out in order to separate the influences of surface micro roughness and subsurface damage on the haze value. The contribution of subsurface damage to the haze value can be formulated as the convolution of the damage profile and the transparency function of the incident laser in silicon crystal.

Transferred-film technology provides a path to the integration of self-biased hexaferrite film devices into MMIC circuits. While progress is being made on the growth of thick oriented films of barium hexaferrite doped with aluminum and scandium by pulsed laser deposition or liquidphase epitaxy, we have demonstrated prototype devices using available yttrium-iron-garnet films and thinned bulk hexaferrites. Insertion losses less than 2dB and isolation greater than 20dB have been demonstrated, and theoretical modeling indicates that insertion losses less than 0.5 dB are accessible with optimized materials and through matching the active circuit components to the ferrite device. The prospects of accessing ferrite non-reciprocal, non-linear, and tunable functions at frequencies up to and exceeding 100 GHz through devices integrated onto microwave IC substrates without the use of DC biasing magnets are the driving force of this research.

Usual vector measurements need to compare the signal detected through the Device Under Test DUT, with the signal coming directly from the source. Thanks to a very simple original method developed since 1989, vector detection can also be done with a purely electronic reference. In transmission experiments, there is no need for any directional coupler, and the frequency coverage extends from 8 to 1000 GHz. Quasi-optical propagation is used in the millimeter-submillimeter frequency range. Transmission through dielectric slabs in free space will give an easy measurement of the permittivity. Its real part will be obtained from the phase rotation, and its imaginary part from the amplitude decay. With dielectric coating deposited onto metal, the reflection method is necessary for the characterization. Low-loss materials are characterized with the open cavity perturbation technique. Extremely low loss materials can constitute “whispering gallery” resonators, very easy to excite and characterize.