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High-performance bandpass and bandstop microwave coplanar filters, which operate from 22 to 91 GHz, have been fabricated on Si substrates. This was achieved using an optimized proton implantation process that converts the standard low-resistivity (∼10 Ω · cm) Si to a semi-insulating state. The bandpass filters consist of coupled lines to form a series resonator, while the bandstop filter was designed in a double-folded short-end stub structure. For the bandpass filters at 40 and 91 GHz, low insertion loss was measured, close to electromagnetic simulation values. We also fabricated excellent bandstop filters with very low transmission loss of ∼1 dB and deep band rejection at both 22 and 50 GHz. The good filter performance was confirmed by the higher substrate impedance to ground, which was extracted from the well-matched S-parameter equivalent-circuit data. [ABSTRACT FROM AUTHOR]

Studies the crystal structure of yttrium barium copper oxide thick films grown on strontium titanate substrate using high-resolution X-ray scattering via synchrotron radiation. Two major components of the films; Observation of ultra-high quality film signature in low index Bragg reflections; Superconducting properties.

GaN p-i-n ultraviolet (UV) photodetectors (PDs) with a low-temperature (LT)-AlN interlayer were proposed and fabricated. It was found that the dark current of such detectors is as small as 28pA even at a high reverse bias of 40 V. Although the high potential barrier at the AlN-GaN interface would slightly reduce the responsivity of PD under low reverse biases, the high UV-to-visible rejection ratio of the PD with an LT-AlN interlayer could be achieved under high reverse biases due to its very low dark current. The rejection ratio of the PD with the LT-AlN interlayer is as large as 735 at the reverse bias of 40 V. [ABSTRACT FROM PUBLISHER]

Gallium nitride p-i-n ultraviolet photodiodes (PDs) with a titanium dioxide (TiO2) nano-particles roughened surface have been fabricated. It was found that the responsivity and external quantum efficiency can be improved 60% on the surface roughened PDs. It was also found that light absorption can be enhanced from various incident angles by the TiO2 roughened surface. Furthermore, the high detectivity of 9.2 times 1013 cmldrHz1 /2ldrW-1 can be achieved from the PD with a rough surface. [ABSTRACT FROM PUBLISHER]

We have improved the performance of integrated antennas on Si for possible application in wireless communications and wireless interconnects. For practical VLSI integration, we have reduced the antenna size and optimized the proton implantation to a low energy of ∼4 MeV with a depth of ∼175 μm. To avoid any possible contamination, the ion implantation is applied after device fabrication. Excellent performance such as very low RF power loss up to 50 GHz, record high 103 GHz antenna resonance, and sharp 5 GHz bandwidth have been achieved. [ABSTRACT FROM PUBLISHER]

We have improved the Q-factor of a 4.6 nH spiral inductor, fabricated on a standard Si substrate, by more than 60%, by using an optimized proton implantation process. The inductor was fabricated in a 1-poly-6-metal process, and implanted after processing. The implantation increased the substrate impedance by ∼ one order of magnitude without disturbing the inductor value before resonance. The S-parameters were well described by an equivalent circuit model. The significantly improved inductor performance and VLSI-compatible process makes the proton implantation suitable for high performance RF ICs. [ABSTRACT FROM PUBLISHER]

Discusses the measurement of very-low-transmission line noise of < 0.25 decibels at 18 gigahertz and low power loss < 0.6 decibels at 110 gigahertz on transmission lines fabricated on proton-implanted silicon. High isolation impedance to ground of proton-implanted silicon; Formation of the transmission lines at a reduced implantation energy.

We report a very simple process to fabricate high performance filter on Si at 40 GHz using proton implantation. The filter has only -3.4-dB loss at peak transmission of 40 GHz with a broad 9-GHz bandwidth. In sharp contrast, the filter on 1.5-μm SiO2 isolated Si has much worse transmission and reflection loss. This is the first demonstration of high performance filter at the millimeter-wave regime on Si with process compatible with current VLSI technology. [ABSTRACT FROM PUBLISHER]

We report the fabrication of orange light-emitting diodes (LEDs) by introducing Te into the well layers of ZnCdSe-ZnSSe multiple quantum-well active region. It was found that a 15% Te can result in a 91 nm photoluminescence (PL) red-shift at 16 K and a 81 nm PL red-shift at room temperature. Such a ZnSe-based orange LED can be integrated easily with conventional ZnSe-based blue-green LED on the same GaAs substrate. Thus, such a ZnSe-based orange LED is potentially useful in realizing a new one-chip type white LED without the use of phosphor. [ABSTRACT FROM PUBLISHER]

High-quality quaternary ZnSTeSe epitaxial layers were successfully grown by molecular beam epitaxy (MBE). It was found that a ZnS0.18 Se0.82 layer was automatically formed in between the ZnSe buffer layer, and the ZnS0.17Te0.08Se0.75 epitaxial layer, when we increased the ZnS cell temperature. ZnSTeSe metal-semiconductor-metal (MSM) photodetectors were also fabricated for the first time. It was found that we could achieve a photocurrent to dark current contrast higher than five orders of magnitude by applying a 10-V reverse bias. We also found that the maximum photoresponsivity is about 0.4 A/W under a 10-V reverse bias. Such a value suggests that the ZnSTeSe MSM photodetector is potentially useful in the blue-UV spectral region [ABSTRACT FROM PUBLISHER]