The feasibility of producing erbium-doped silicon light-emitting diodes by molecular beam epitaxy is demonstrated. The p-n junctions are formed by growing an erbium-doped p-type epitaxial silicon layer on an n-type silicon substrate. When the diodes are biased in the forward direction at 77 K they show an intense sharply structured electroluminescence spectrum at 1.54 μm. This luminescence is assigned to the internal 4f–4f transition 4I13/2→4I15/2 of Er3+ (4f11).

Ground planes of conductor-backed coplanar waveguides (CBCPWs) behave like overmoded patch antennas supporting parallel-plate modes and show numerous resonances. For typical monolithic-microwave integrated-circuit chip sizes, these unwanted resonance frequencies lie within the microwave and millimeter-wave frequency region. Due to this feedback mechanism, today's coplanar millimeter-wave amplifiers operating up to 250 GHz require special packaging techniques for stable operation. The use of vias is one method of suppressing parallel-plate modes. The effect of via-holes within a ground plane and the effect of an open or a shorted ground-plane periphery on the parallel-plate modes of CBCPWs were investigated in depth up to 200 GHz for quartz and GaAs substrates. It is shown that the placement of the vias within the coplanar-waveguide structure is crucial for the suppression of parallel-plate modes. If properly placed, vias are an effective means to suppress these unwanted modes over a chosen frequency range

The performances of two different interconnection techniques for coplanar MMICs, wire bonding and flip chip, are investigated at millimeter-wave frequencies. By developing an accurate model for the interconnections, which is validated with experimental data up to 120 GHz, the limitations with respect to frequency and interconnection distance of either technique are pointed out, yielding useful data for the design of hybrid MMW-subsystems

Two compact single-chip 94-GHz frequency-modulated continuous-wave (FMCW) radar modules have been developed for high-resolution sensing under adverse conditions and environments. The first module contains a monolithic microwave integrated circuit (MMIC) consisting of a mechanically and electrically tunable voltage-controlled oscillator (VCO) with a buffer amplifier, 10-dB coupler, medium-power and a low-noise amplifier, balanced rat-race high electron-mobility transistor (HEMT) diode mixer, and a driver amplifier to increase the local-oscillator signal level. The overall chip-size of the FMCW radar MMIC is 2 x 3.5 mm2. For use with a single transmit-receive antenna, a 94-GHz microstrip hexaferrite circulator was implemented in the module. The radar sensor achieved a tuning range of 1 GHz, an output signal power of 1.5 mW, and a conversion loss of 2 dB. The second FMCW radar sensor uses an MMIC consisting of a varactor-tuned VCO with injection port, very compact transmit and receive amplifiers, and a single-ended resistive mixer. To enable single-antenna operation, the external circulator was replaced by a combination of a Wilkinson divider and a Lange coupler integrated on the MMIC. The circuit features coplanar technology and cascode HEMTs for compact size and low cost. These techniques result in a particularly small overall chip-size of only 2 x 3 mm2. The packaged 94-GHz FMCW radar module achieved a tuning range of 6 GHz, an output signal power of 1 mW, and a conversion loss of 5 dB. The RF performance of the radar module was successfully verified by real-time monitoring the time flow of a gas-assisted injection molding process

The impact of the packaging configuration on cross talk and feed back effects caused by parasitic substrate modes is investigated for coplanar millimeter-wave circuits. It is demonstrated theoretically and by means of several circuit examples that both the mounting configuration and the thickness of the semiconductor substrate of coplanar MMICs have to be chosen appropriately, in order to avoid circuit degradation or even failure

The characteristic 1.54-μm emission from the rare-earth element erbium implanted in GaAs, InP, and GaP was investigated through 10-K photoluminescence essentially as a function of anneal temperature, time, and method. The strip-heater, forming-gas, and quartz-ampoule anneal methods were utilized in the range of 400 to 1000 °C. Erbium-related emissions were observed from 1.48 to 1.64 μm and were observable at emission temperatures of up to 260 K for InP:Er and 296 K for GaP:Er and GaAs:Er. Out of the three semiconductors, GaAs:Er was observed to exhibit the highest optical activation using a square-profile implantation technique. Dependent on the anneal method, optimum Er emissions occurred between 650 and 800 °C for GaAs, for InP between 575 and 625 °C, and for GaP between 800 and 950 °C. In general, the forming-gas anneal method proved most successful; however, maximum luminescence including sharper emission lines was achieved through the strip-heater method. This method, with an anneal time of 10 s, showed also the importance of short-time anneals in GaAs:Er, results which were also paralleled by isothermal anneals of InP:Er. The difference in emissions at different anneal temperatures and times gives preliminary evidence of different Er3+ centers.

Extensive attenuation data of coplanar lines on semi-insulating GaAs and InP is presented over the frequency range 1-60 GHz. On-wafer measurements were used to obtain the S-Parameters. A ground-to-ground spacing of 30,60,90 and 120 mm, typical for that used in todays microwave and millimeterwave integrated circuit applications, was investigated. The center line width (impedance) and the evaporated gold metal thickness were varied. For the frequency range investigated (metal thickness less than 2-3 times the skin depth), the attenuation was found to be inversely proportional to the metal thickness. The attenuation varies with frequency as fhighn, with n smaller than 0.5

A new integrated W-band frequency source MMIC is presented which consists of a 94-GHz voltage-controlled oscillator (VCO) with large tuning range and a phase comparator, forming a subharmonic injection-locked phase-locked loop (ILPLL). The ILPLL combines conventional injection-locking with an additional phase control loop to improve the locking range of the oscillator significantly. The 4th subharmonic frequency is used as the reference signal. The locking range was increased from 80 MHz without ILPLL to 4.5 GHz with ILPLL by closing the loop with an external dc amplifier. A phase noise of -83 dBc/Hz at 100-KHz offset was achieved. Pseudomorphic GaAs HEMT's and a coplanar circuit topology were used to allow integration into complex single-chip subsystems and flip-chip packaging