Heribert Eisele

Recent advances in the performance of InP Gunn devices and GaAs TUNNETT diodes for the 100-300-GHz frequency range and above

Improved heat dissipation in InP Gunn devices resulted in RF power levels exceeding 200, 130, 80, and 25 mW at oscillation frequencies of around 103, 132, 152, and 162 GHz, respectively. Corresponding dc-to-RF conversion efficiencies exceeded 2.3% from 102 to 132 GHz. Power combining increased the available RF power levels to over 300 mW at 106 GHz, around 130 mW at 136 GHz, and more than 125 mW at 152 GHz with corresponding combining efficiencies from 80% to over 100%. Operation in a second harmonic mode yielded RF power levels of more than 3.5 mW at 214 GHz, over 2 mW around 220 GHz as well as over 1 mW around 280, 300, and 315 GHz. RF power levels exceeding 10 mW at 202 GHz, 9 mW around 210 GHz, and 4 mW around 235 GHz were obtained from GaAs TUNNETT diodes in a second harmonic mode as well. Corresponding dc-to-RF conversion efficiencies were around 1% at 202 and 210 GHz.

Two-terminal millimeter-wave sources

Basic principles of operation, fundamental power-generation capabilities, and fabrication technologies are reviewed for three groups of two-terminal devices, i.e., resonant-tunneling diodes (RTDs), transferred-electron devices (TEDs), and transit-time diodes. The paper focuses on devices for frequencies above 30 GHz, and an overview of recent research in this area and of various state-of-the-art laboratory results is given. As an outlook, the potential of some new material systems for high-power devices is discussed.

Terahertz Frequency Detection and Identification of Materials and Objects

Organizing Committee.- Sponsors.- Preface.- Theme 1: Terahertz Devices.- Terahertz Emission from Semiconductors Excited by Ultrafast Laser Pulses A. Krotkus et al.-Terahertz Generation by Multiplication J. Stake et al.- Towards Superlattice THz Amplifiers and Lasers A. Lisauskas et al.- Tailoring the Emission of Terahertz Quantum Cascade Lasers R. Green et al.- Guided Propagation of Terahertz Pulses on Metal Wires K. Wang and D.M. Mittleman.- Superlattice and Other Negative-Differential Resistance Devices: Current Status H. Eisele.-Theme 2: Interactions.- Molecular and Organic Interactions A.G. Davies and E.H. Linfield .- Terahertz Beam Interactions with Amorphous Materials M. Naftaly and R.E. Miles.- Development of Tagless Biosensors for Detecting the Presence of Pathogens Jing-Yin Chen et al.- Theme 3: Detection and Sensing.-Improvements to Electronic Techniques for THz Spectroscopic Detection D.W. van der Weide et al.-Terahertz Time-Domain Spectroscopy of Crystalline and Aqueous systems P.U. Jepson et al.- Continuous-Wave Terahertz Photomixer Systems For Real World Applications I.S. Gregory et al.- Theme 4: Systems for Security.- Systems Requirements for A Multi-Channel THz Contraband Scanner W.S. Truscott.- Challenges to THz Counter Terrorism & Security Related Applications H. Cummins.- Terahertz Detection of Illegal Objects R. Appleby et al.- THz Rays to Detect Drugs of Abuse K. Kawase et al.-Terahertz Spectroscopy for Explosive, Pharmaceutical and Biological Sensing Applications Hai-Bo Liu and Xi-Cheng Zhang.- Terahertz Communications: a 2020 vision M. Koch.- Theme 5.- Applied Terahertz Science: The Technology of the Future, and Always Will Be? M. Chamberlain.- List of Speakers.- List of participants.- Group Photograph.- Index.-

Submillimeter-wave InP Gunn devices

Recent advances in design and technology significantly improved the performance of low-noise InP Gunn devices in oscillators first at D-band (110-170 GHz) and then at W-band (75-110 GHz) frequencies. More importantly, they next resulted in orders of magnitude higher RF output power levels above D-band and operation in a second-harmonic mode up to at least 325 GHz. Examples of the state-of-the-art performance are continuous-wave RF power levels of more than 30 mW at 193 GHz, more than 3.5 mW at 300 GHz, and more than 2 mW at 315 GHz. The dc power requirements of these oscillators compare favorably with those of RF sources driving frequency multiplier chains to reach the same output RF power levels and frequencies. Two different types of doping profiles, a graded profile and one with a doping notch at the cathode, are prime candidates for operation at submillimeter-wave frequencies. Generation of significant RF power levels from InP Gunn devices with these optimized doping profiles is predicted up to at least 500 GHz and the performance predictions for the two different types of doping profiles are compared.

High-performance InP Gunn devices for fundamental-mode operation in D-band (110-170 GHz)

InP Gunn devices with an n/sup +/nn/sup +/ structure and a graded doping profile in the active region were designed, fabricated, and tested for fundamental-mode operation at D-band frequencies. Improved heat dissipation significantly increased the available RF output power and power levels of more than 90 mW up to frequencies around 135 GHz, more than 130 mW at 131.7 GHz, and more than 60 mW at 151 GHz are achieved in fundamental-mode operation. These are the highest RF power levels reported to date from any Gunn devices. These InP Gunn devices with dc-to-RF conversion efficiencies up to 2.5% around 132 GHz also exhibit excellent noise performance and the typical phase noise up to the highest RF power levels is well below -100 dBc/Hz, measured at a frequency off-carrier of 500 kHz. >

Selective etching technology for 94 GHz GaAs IMPATT diodes on diamond heat sinks

Abstract A selective etching technology has been established for 94 GHz GaAs IMPATT diodes operating on diamond heat sinks. Using this technology diodes were realized delivering an output power of 270 mW. The corresponding efficiency was 5.7% at an oscillation frequency of 95 GHz.

D-band (110–170 GHz) InP gunn devices

Abstract This paper reports on the development of InP Gunn sources for operation in the D-band (110–170 GHz). n + − n − n + structures with flat doping as well as graded doping profiles have been considered. Oscillations were obtained at 108.3 GHz from a 1 μm structure with a uniform n doping of 2.5 × 10 16 cm −3 . The CW RF output power was 33 mW. A 1 μm graded structure with an n doping increasing linearly from 7.5 × 10 15 to 2.0 × 10 16 cm −3 has resulted in 20 mW at 120 GHz and 10 mW at 136 GHz. These results are believed to correspond to a fundamental mode operation and represent the state-of-the-art performance from InP Gunn devices at these frequencies. This improvement in performance is attributed in part to a processing technique based on the use of etch-stop layers and InGaAs cap layers. An etch-stop layer allows low-profile mesas (2–3 μm) and InGaAs cap layers help reduce the contact resistance, thus minimizing series resistances in the device. In addition, a physical model based on the Monte Carlo method was developed to aid in the design of structures for high frequency operation. Experimental results obtained from a 1.7 μm Gunn device operating at W-band frequencies were used to estimate appropriate InP material parameters.

An all solid-state 640 GHz subharmonic mixer

This paper reports on the first all solid-state two-diode subharmonically pumped (SHP) mixer operating at 640 GHz. The required local oscillator (LO) power is less than 4 mW at 320 GHz for optimum performance. Two approaches are used to generate the required LO power. The first approach utilizes a 107 GHz InP Gunn diode followed by a whisker-contacted tripler while the second employs an IMPATT diode at 80 GHz followed by two planar diode frequency doublers. The best measured mixer noise temperature is 2500 K double sideband with a conversion loss of 9 dB at an IF of 2 GHz. An IF-frequency scan of the mixer shows a noise temperature of no worse than 3700 K across the 1.5 to 15 GHz band. Extraneous LO noise from the IMPATT is not evident for the SHP mixer, even at those frequencies and with low IFs. This performance represents the state-of-the-art for room temperature subharmonic mixers operating at these frequencies. The mixers are being developed for NASAs Mission to Planet Earth.

Superlattice electronic devices as high-performance oscillators between 60-220 GHz

Negative differential resistance devices were fabricated from four epitaxial wafers with different GaAs/AlAs superlattices and evaluated in resonant-cap full-height waveguide cavities. These devices generated output powers in the fundamental mode between 62–108 GHz. The best RF powers were 58 mW at 66 GHz, 42 mW at 78 GHz, and 28 mW at 94 GHz. The RF power of 15 mW at 101 GHz constitutes a 30-fold improvement over previous results; the highest fundamental oscillation frequency was 108 GHz. In a second-harmonic mode, one device yielded 2.0 mW at 216 GHz, the highest second-harmonic frequency to date for a GaAs/AlAs superlattice.

Efficient power combining with D-band (110-170 GHz) InP Gunn devices in fundamental-mode operation

D-band InP Gunn devices on diamond heat sinks with an n/sup +/n/sup -/n/sup +/ structure and a graded doping profile in the active region were tested as free-running oscillators in individual resonant-cap full-height waveguide cavities. Subsequently, matched oscillators were power-combined in an in-line dual-cavity configuration. Combined radio frequency (RF) power levels of more than 300 mW at 106 GHz, 130 mW at 136 GHz, and more than 100 mW at 152 GHz were achieved. These RF power levels are the highest reported to date from either single or power-combined Gunn devices at W-band and D-band frequencies. They correspond to combining efficiencies of more than 80%, 86%, and more than 100% as well as overall DC-to-RF conversion efficiencies of 1.95%, 1.25%, and 0.90%, respectively. Similar to oscillators with single devices, these power-combined Gunn device oscillators exhibit good tunability and a phase noise of well below -100 dBc/Hz, measured at a frequency off the carrier of 500 kHz.