film-diode process – a breakthrough technology for …...over full if-band. rpg 183ghz mixer with...

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By Dr.-Ing. Oleg Cojocaricojocari@acst.de

Technology Solutions for THz-Electronics

Film-Diode Process –a breakthrough technology for THz-Electronics

ACST GmbHJosef-Bautz-Str. 15, 63457 Hanau

www.acst.de

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eACST GmbH: Company profileACST GmbH: Company profile

Founded in 2006 as a Spin-Off from TU Darmstadt

First European commercial supplier of Schottky components for THz-Applications Originally-developed fabrication technology, particularly developed for mm-wave and THz-applications Discrete and monolithically-integrated Schottky-structures with state-of-the-art performance So far the only European supplier of Zero-Bias Diodes for THz-applications

Close collaboration with leading institutions concerning development of THz-technology Space agencies (ESA, DLR,CNES) Universities (TU Darmstadt, TU Berlin, TU Duisburg, TU Erlangen-Nuremberg, …) International industry partners

Leading Schottky technology with state-of-the-art performance First ultra-wideband Schottky detector (75GHz-1.5THz, in year 2008) First all-European 660GHz Heterodyne receiver with unprecedented performance Integrated RTD-oscillator with highest ever reported oscillation frequency (1,111 THz)

Anticipated participation in ESA MetOp Second Generation Program

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ePlanar and vertical structuresPlanar and vertical structures

Vertical structure

Planar structure

Uniform distribution of the current density across contact areaBack-side processing

required

No back-side process needed

Nonuniform distribution of the current density

Semiconductor

Schottky Ohmic

Semiconductor

Schottky

Ohmic

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eQVD Design ConceptQVD Design Concept

Whisker-Contacted Diodes (WCD)

Quasi-Vertical Diode (QVD)

Vertical structure Low parasitics

Quasi-vertical structure Reduced series resistance Good heat-sink Suitable for integration.

Unreliable contact No integration possible

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eThermal simulationsThermal simulations

Quasi-Vertical Diode (QVD)

Air-bridge5µm anode

Back-side contact pad

Planar Surface Channel Etched Diode (SCE)

Anode-lead5µm anode

Contact pad(flip-chip)

Whisker-contacted diode (WCD)

Whisker

70μm thickGaAs

Whisker

70μm thickGaAs

Contact pad

5µm anode

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eComparative simulation resultsComparative simulation results

0 20 40 60 80 1000

50

100

150

200

250

300

350

Max

. tem

pera

ture

, K

Dissipated power, mW

QVD WCD SCE

0 20 40 60 80 1000

50

100

150

200

Max

. tem

pera

ture

, KDissipated power, mW

h=1m h=2m h=3m h=4m h=5m

The impact of mesa thicknesson thermal performance of a QVD

Comparative results of considered structures

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eACST APD by FDACST APD by FD--processprocess

• Quasi-vertical approach

• Transferred membrane substrate

• Suitable for both discrete structures and integrated circuits

• Accommodates beamleads, MIM-capacitors, two-level wiring…

• Aims at ultimate performance at MM/SubMM waves

APD side-view APD front-view

90µm

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e332GHz Doubler IC332GHz Doubler IC

In collaboration with RPG Radiometer Physics GmbH

Fabricated 332GHz doubler Integrated Circuit

332GHz Doubler IC mounted in a WG332GHz Doubler IC mounted in a WG--BlockBlock

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e332GHz Doubler performance332GHz Doubler performance

• Limited input power of about 40mW-50mW is insufficient to fully characterize the doubler. • No sign of saturation: fully-pumped doubler should provide more output power.• Higher input power would result in a higher output power.

In collaboration with RPG Radiometer Physics GmbH

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e332GHz Tripler IC332GHz Tripler IC

Diodes

Heat-spreader

BeamleadsIC Front-side IC Back-side

In collaboration with RPG Radiometer Physics GmbH

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Typical conversion gain and noise temperature of a 183GHz

subharmonic (LOx2) mixer.

Integration times up to 200 sec. show no sign of instabilities or deviation from the radiometer law.

Allan Variance of a 183GHz mixer, operating in a switched-noise

stabilised radiometer.

Noise temperature less than 500K over full IF-band.

RPG 183GHz mixer with ACST APDRPG 183GHz mixer with ACST APD

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Tsys=1800 K

Tmix=800 to 1200 K

Conversion= –7 dB

LO Power: 5 mW

RPG 424GHz mixer with ACST APDRPG 424GHz mixer with ACST APD

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eFabricated 664GHz Mixer ICFabricated 664GHz Mixer IC

IF-outputLO-input

Supporting Beamleads

APD-Diode

Membrane-Substrate

Side view of a free-standing ICMeasured mixer performance

In collaboration with RPG Radiometer Physics GmbH

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In collaboration with RPG Radiometer Physics GmbH

First allFirst all--European 664GHz receiver systemEuropean 664GHz receiver system

664GHz Mixer mounted with test horn, 332GHz Tripler, Isolator, powerful W-band source (x6 internal)

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eZeroZero--Bias Detector diodesBias Detector diodes

Low video-resistance / high current responsivity; Optically-transparent membrane-substrate ; Suitable for monolithic integration (THz-MIC); The technology is suitable for frequencies well beyond1THz.

DC-Diode characteristicsDiscrete Diode mounted on CPW

Back-side contact pads

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• InGaAs built-in voltage (barrier height) significantly lower than GaAs (0.2eV compared to 0.8eV)

• (Reduced LO power required for SHM at 183 GHz: 0.34 mW (10 dB less!)

183 GHz InGaAs mixer with different LO-power

3.0 mW2.2 mW

0.34 mWLOPower

–5.5 dB–4.2 dB

–6.6 dBConv.Loss

500 K430 K

700 KTmix

GaAsInGaAs183GHz

183GHz mixer with ACST InGaAs diode183GHz mixer with ACST InGaAs diode

In collaboration with RPG Radiometer Physics GmbH

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eAchieved Performance (RPG)Achieved Performance (RPG)

Doubler Input power

Output Power

Efficiency DC Bias

44mW 11mW >20% 7V

Tripler Input power

Output Power

Efficiency DC Bias

67mW 6mW 9% 8V

Frequency Conversion L LO power Noise temperature Noise temperature (old)

183GHz InGaAs -6.5dB (DSB) 0.34 mW Tsys 800K (DSB no correction)Tmix 700K

-

183GHz GaAs -4.2dB (DSB) 2 mW Tsys 525K (DSB no correction)Tmix 430K

Tsys 750K (-6.0dB L) RPG

432GHz GaAs -7.0dB (DSB) 5 mW Tsys 1700K (DSB no correction)Tmix 1100K

Tsys 2700K (-9.7dB L) RPG

660GHz GaAs Integrated

-8.0dB (DSB) 4mW Tsys 2300K (DSB no correction)Tmix 1600K

-

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eACST THz Detector ModuleACST THz Detector Module

Si-Lens

Antenna

Zero Bias Diode

Pre-Amp

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eAntenna integrated ZeroAntenna integrated Zero--Bias diodeBias diode

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eUWB measurements at TUDUWB measurements at TUD

Photoconductive generated CW THz signal modulated with 200kHz.

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eUWB measurement resultsUWB measurement results

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eFTIR measurements at DLRFTIR measurements at DLR

Courtesy of the department THz-Instrumentierung, Institut für Planetenforschung

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eResponse time measurement at ANKAResponse time measurement at ANKA

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eDetector response timeDetector response time

• Real pulse length in the accelerator: about 14ps.• Detector response: about 25ps. The delay is considered to be due to

limitations of the SMA connector.• HTS (YBCO) hi-temperature superconductor. -detector-20ps.

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eRTDRTD--based THzbased THz--MICMIC

Free-standing THz-MICRadiating

Vivaldy-antenna

Slot antenna resonator

Insulator Membrane-substrate

Contact padsfor DC-bias

RTD

In collaboration with TUD

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Mounted circuit by thermo-compression via insulator membrane

Gold-bump Array on contact-pads

Si-Substrate

Thin-filmresistor

Gold-bumps are used to increase local pressure while keeping low total pressure on the pad.

Mounting approachMounting approach

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eAssembled RTDAssembled RTD--oscillatoroscillator

MIM

In collaboration with TUD

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eMeasured resultsMeasured results

Oscillation frequencies up to 1111GHz. This is the highest RTD-oscillation frequency reported so far.

In collaboration with TUD

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Thank You !Thank You !