CVD Diamond based Active Devices Paolo Calvani S2DEL DiaC2Lab (Diamond & Carbon Compounds Lab) IMIP - CNR - Montelibretti (RM) S2DEL Solid State and Diamond Electronics Lab Università degli Studi “Roma Tre”

Daniele M. Trucchi Paolo Calvani Alessandro Bellucci Emilia Cappelli Stefano Orlando

CNR-IMIP: Know-How & Projects 1989-1995 Study of Nucleation and Growth Mechanisms of CVD Diamond 1995-1999 CVD Diamond protective coatings of cutting tools Coordination of MURST-CNR 5% Project 2003-2006 Development of high-tech materials and ceramic coatings ENEA-MIUR “PROMOMAT” Strategic Project 1999-2001 Secondary electron emission amplifiers for scanning electron microscopy MADESS II Applied Research Project 2000-2002 VUV & DUV Radiation Detectors in collaboration with S2DEL – Univ. Roma Tre ASI ARS1/R07/01 Aerospace Project 2001-2005 Poly-Diamond Radiation Dosimeters for Radiation Therapy Coordination of European Project “DIAMOND” G5RD-CT01-00603 2003-2007 Nanostructured Carbon and graphene Structures for Opto-Electronic applications FIRB Project “Micro & Nanocarbon” & FISR Project “High Density Memories” 2008-2010 Systems for direct nuclear-to-electric energy conversion Coordination of CNR-RSTL “ECO-Diamond” Project 2008-today Development of Single-Crystal Diamond dosimeters in collaboration with S2DEL - Univ. Roma Tre 2010-2013 Thermionic-thermoelectric conversion module for solar concentrated systems E2PHEST2US Project Mechanical Applications Electronic Applications

Secondary Electron Emission Characterization Setup CNR-IMIP: Facilities Material Production Characterization of Chemical-Physical Properties Technological Processes for Device Fabrication Characterization of Device Performance ~ Vacuum & Temperature Electronic Characterization (VTEC) (10-9 Torr, T=77-1200 K) for Thermionic Emission Secondary Electron Emission Characterization Setup Spectroscopy Raman & IR Hot Filament CVD for diamond film deposition MW-CVD for surface hydrogen termination Spectral (UV-Vis-NIR) Photoconductivity Setup X-Ray Photoconductivity Setup Microwave CVD for diamond (doped) film deposition RF Sputtering for deposition of metals Ti, Al, Cr, … Spectral Photometry Microscopy SEM & EDS Four-Point Probe under vacuum, T=25-400 °C Pulsed laser (Excimer & Nd:YAG) ablation for (nanostructured) thin-film deposition of carbon, carbides, refractory metals AFM Seebeck Effect Measurement System for Thermoelectric Characterization

Diamond Electronic Properties Material Band gap Thermal conductivity Breakdown electric field Eb Mobility Carriers sat. velocity vsat Dielectric constant εr eV W/cmK 106 V/cm cm2/Vs 107 cm/s - Diamond 5.5 20 10 2000 - h 1.0 5.7 Gallium nitride 3.4 1.5 2.5 2000 8.9 Silicon carbide 3.27 4.9 3.0 1000 2.0 9.7 Gallium Arsenide 1.42 0.55 0.4 8500 1.29 12.9 Silicon 1.12 0.3 1400 11.8 Germanium 0.67 0.58 0.1 3900 16.2 High Frequency – High Power Field Effect Transistors UV Power Switches Renewable Energies Conversion Stages

High Frequency – High Power Field Effect Transistors S2DEL Plasma assisted Hydrogen termination of CVD Diamond induces p-type conductive channel Fabricated by S2DEL and IFN-CNR Evolution of the band bending, activated by air exposure, during the electron transfer process at the interface between diamond and water layer[b]: density-of-states (DOS) is changing from 3D to 2D: 2DHG

Pout @ 1GHz ~ 0.8 W/mm[a] S2DEL Maximum VDS applied=80 V RF Power Characterization by Politecnico di Torino CLASS A @ 2GHz Pout=0.2 W/mm Gain=8 dB PAE=21.3% Pout @ 1GHz ~ 0.8 W/mm[a] Best result for Polycrystalline Diamond S2DEL LG=200nm, WG=50um VDS=-14 V, VGS=-0.3 V fMAX = 15.2 GHz ft = 6.2 GHz Maximum VDS applied=80 V Eapplied= 2 MV/cm Channel conductance is always positive. No self heating effects!

LG=0.2 μm VGS=-0.2 V, VDS=-10 V Eapplied= 0.5 MV/cm Polycrystalline Diamond PolyD4 by Russian Academy of Sciences Single Crystal Diamond P7MS by Russian Academy of Sciences Wg=50 μm -20 dB/dec. WG=25 μm Gain = 15 dB@ 1 GHz Gain = 22 dB @ 1 GHz fMAX = 23.7 GHz fMAX =26.3 GHz fT = 6.9 GHz fT = 13.2 GHz S2DEL LG=0.2 μm VGS=-0.2 V, VDS=-10 V Eapplied= 0.5 MV/cm RF Small Signal Characterization in collaboration with by Tor Vergata University

Polycrystalline Diamond PolyD4 by Russian Academy of Sciences S2DEL -20 dB/dec. Lg=0.2 μm, Wg=25 μm VGS=0.0 V, VDS=-35 V Gain = 16 dB @1GHz fMAX = 35 GHz fT = 10 GHz Eapplied= 1.75 MV/cm

S2DEL

Neweks PSX 100 excimer laser Filled with ArF gas mixture UV POWER SWITCHES S2DEL DUT 50 Oscilloscope input resistance Lecroy WavePro 960 2 GHz 16Gs/s digital oscilloscope Picosecond 5550B 18 GHz Bias tee VDS =193 nm Si diode (for trigger) Neweks PSX 100 excimer laser Filled with ArF gas mixture x Laser pulse shape recorded by vacuum phototube GPIB VGS (Keithley 617) 11

UV generated carriers VDS=-9.6 V VGS=-3.4 V 12/23 Source Drain G diamond VDS=-9.6 V VGS=-3.4 V 12

13/23 Source Drain G UV generated carriers diamond

Renewable Energies Conversion Stage EU Project E2PHEST2US’ Duration: 3 years (Jan 2010 - Jan 2013) Total Project Cost: 2.68 M€ Total EU Funding: 1.98 M€ Partners: CNR (Italy, Scientific Coordination) CRR (Italy, Management Coordination) SHAP (Italy) Tel Aviv University (Israel) Tubitak (Turkey) Prysmian (Multinational Industry) Maya (San Marino) *For details, http://www.ephestus.eu

EU Project E2PHEST2US’ T z Thermionic Stage Load Radiation Absorber Collector Thermoelectric Stage Load Rload Rload p n Under Vacuum Concentrated Solar Radiation (400 – 1000 suns) p n p n Thermionic Emitter Inter-electrode Space (<1 mm) Development of: A radiation absorber made of ceramic materials able to work stably at high temperature (700 - 1000 °C) A thermionic conversion stage with CVD diamond as the active material A thermoelectric conversion stage constituted by high Seebeck coefficient materials Maximum theoretical efficiency ≈ 30% T z Final Thermal Stage TR (700-1000 °C) Thermoelectric Stage TE TC (250-400 °C) TTE TAmb *For details, http://www.ephestus.eu

Thanks for the attention CVD Diamond based Active Devices Thanks for the attention S2DEL DiaC2Lab (Diamond & Carbon Compounds Lab) IMIP - CNR - Montelibretti (RM) S2DEL Solid State and Diamond Electronics Lab Università degli Studi “Roma Tre”

Alternative Technology in Concentrating Systems Multi-junction Photovoltaic Cells Thermodynamic Conversion by Heat Engines (Stirling, Rankine) Nominal Conversion Efficiency of 30% Compactness No mechanical parts in movement Highly Expensive Mandatory Need of Cooling (Conversion Efficiency Exponentially Decreases with Temperature) Illumination Local Inhomogeneities Causes Output Bottlenecks Production Dependent on Semiconductor Industry (Few Large-Scale World Suppliers) Nominal Conversion Efficiency of 35% at High Temperatures (> 600 °C) Not Compact System Mechanical Parts in Movement (Degradation with Operative Time) Economically Reasonable for Large Plants (> 10 kWe)