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Applications of diamond films

Lecture 5. Applications of diamond films. CVD diamond devices and components. microwave transistor on diamond wafer. Cutting tools. UV and X-ray detectors. IR windows for gyrotron and CO 2 lasers. thin membranes. X-ray lenses and screens. CVD diamond thermal spreaders

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Applications of diamond films

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  1. Lecture 5 Applications of diamond films

  2. CVD diamond devices and components microwave transistor on diamond wafer Cutting tools UV and X-ray detectors IR windows for gyrotron and CO2 lasers thin membranes X-ray lenses and screens

  3. CVD diamond thermal spreaders for microwave electronic devices (transistors). Examples of size: 4.6х0.9х0.5 мм 8.6х1.4х0.5 мм

  4. Thin diamond films on AlN ceramics V.G. Ralchenko, Russian Microelectronics, 2006, Vol. 35, No. 4, p. 205. ◄ Coated with black diamond AlN before diamond ► deposition growth rate 7.9 μm/h; film thickness up to 150 μm Thermal conductivity measurements by laser flash technique AlN dielectric heat spreader, 18 mm diameter. Diamond coating increases thermal conductivity from 1.7 to 10.0 W/cmK.

  5. CVD diamond detectors Charge collection distance d = µτE RD42 Collaboration (CERN) data for De Beers CVD diamond samples (poly): d = 200 µm (year 2000) dmax≈ 350 µmpresent Stable up to dose ~1015 cm-2 under protons, neutrons, pions. D. Meier, RD42 Collaboration Rep. 1996 GPI samples

  6. CVD diamond UV detectors solar-blind photoresistors Photoresponse of nucleation (1) and growth sides Spectral discrimination UV/Vis of 105. Dark current of the order of 1 pA. Interdigitizing electrodes on polished diamond. Cr(20 nm)/Au(500nm) strips 50 µm wide, the gap between electrodes is 50 µm. V.G. Ralchenko et al. Quantum Electronics (Moscow, 36 (2006) 487.

  7. Spectral Photonductivity: JDoS GPI-RAS Diamond SC CVD diamond UV detectors Band gap Eg = 5.45 eV. Light absorption and e-h pairs generation for photons with λ <225 nm, no absorption in the visible and IR. ► solar-blind radiation-hard photodetectors (no filters are needed) Low surface recombination and small Urbach tail. The recovery of photoconductivity is more than 6 orders of magnitude and saturates around 5 V/µm.

  8. 2D-UV detector: mapping the laser beam 16-pixel matrix sensor on 1 cm2 polycrystalline diamond: G. Mazzeo et al. DRM. 16 (2007) 1053 Rows and columns are electrodes on two sides of the diamond sample. Sensor electronics Output signal : 1 mm2 beam illuminates the pixels along the row direction. measured incident Test monochromatic beam profile

  9. Past UV, X-ray Source Imaging by 2D detectors UV, X-ray Source Imaging • 36-pixel array (0.75 × 0.75 mm2) • Poly 1 cm2 RAS 270 um • Contacts – Ag 50-200 nm • Cu-Ka, 8.05 keV • ArF 193 nm, 3 mW X-ray tube beam profile when scanned across the detector ArF excimer laser beam profile M. Girolami, P. Allegrini, G. Conte, S. Salvatori, D. M. Trucchi, A. Bolshakov, V. Ralchenko “Diamond detectors for UV and X-ray source imaging”, IEEE-EDL 33 (2012) 224-226.

  10. On-line diamond X-ray detectors Diamond membrane: 11 µm thickness, window of 7 mm diameter. X-ray transmission (50 keV) > 98%. Source: X-ray tube with tungsten anode. Electrodes Au/Ti, Ø3 mm. Dark current ~100pA. Photocurrent/dark-current ratio: 8x103 at Ua=50 kV, j=15 mA. V. Dvoryankin et al. Lebedev Physical Institute Reports, No. 9 (2006) 44.

  11. H H-terminated layer diamond p-type conductivity on H-terminated diamond surface: 2D hole layer (111) Surface with C-H bonds Microwave plasma • Surface band bending where valence-band electrons transfer into an adsorbate layer: “transfer doping model”. • Shallow hydrogen induced acceptors. ♦ carriers density value 1013 cm-2 ♦ hole mobility 100-130 cm2/Vs ♦ activation energy 1.6-4.1 meV 1994: H-terminated diamond based FETH. Kawarada, et al., Appl. Phys. Lett. 65 less than 6 nm Hole density is evaluated from C-V characteristics G. Conteet al, NGC 2011, Moscow

  12. Device Technology Issues Device Layout MESFET technology issues Batterfy-shaped design Source(Au) Source(Au) Gate(Al) 25 μm ≤ WG ≤ 200 μm 0.2 μm ≤ LG ≤ 1 μm Small H-terminated area for leakage current reduction and electric field confinement. WG Drain(Au) 2D Hole Channel CVD Diamond

  13. Surface Channel MESFETs Past MESFET frequency characteristics Polycrystalline Diamond RAS PolyD4 Single Crystal Diamond RAS P7MS WG=25 μm Wg=50 μm -20 dB/dec. Gain = 22 dB @ 1 GHz fMAX = 23.7 GHz fMAX =26.3 GHz Gain = 15 dB@ 1 GHz fT = 6.9 GHz fMAX/fT=3.5 fT = 13.2 GHz fMAX/fT=1.8 Eapplied= 0.5 MV/cm VGS=-0.2 V, VDS=-10 V LG=0.2 μm G. Conte, E. Giovine, A. Bolshakov, V. Ralchenko, V. Konov “Surface Channel MESFETs on Hydrogenated Diamond”, Nanotechnology 23 (2012) 025201.

  14. Fast CVD diamond bolometer Very thin buried graphitized layer as resistor. Fast dissipation of absorbed energy – quick response. Fabrication procedure: (i) C+ ion implantation in polished CVD diamond: energy 350 keV, dose 81015cm-2. (ii) Contacts – graphitic pillars by C+ implantation at variable energy of 20 to 350 keV. (iii) Annealing in vacuum at 1500ºC for 1 hour. ► Buried graphite strip: 2 mm total length, 70 μm wide, thickness 220 nm, depth 265 nm. Segments of 70 and 300 μm long. Resistance @298 K is R0=300-1200 Ohm. Linear temperature dependence R(T)=(-1.4710-4 K-1)R0 1- buried graphite; 2 - contacts T.I. Galkina, Physics of Solid State (St. Petersburg), 49 (2007) 621.

  15. Test of diamond bolometer Pulsed irradiation with a nitrogen laser (λ=337 nm, τ~ 8 ns). Beam spot size 90 μm. Layered structure for simulation of the bolometer response kinetics. Measured signal (circles) and modeling (solid line). Response signal ≈20 ns (FWHM), very fast for bolometer-type sensors

  16. Raman diamond lasers use Stimulated Raman Scattering (SRS) pulsed pump Single pass geometry spontaneous RS • ● SRS is observed only at high enough intensities. • ● Advantages of diamond: • large Raman shift 1332 cm-1 • high gain g>11 cm/GW. excitation at λ=1.06 µm; three anti-Stokes lines stimulated RS For polycrystalline CVD diamond: Kaminskii, V. Ralchenko, et al. Phys. Stat. Sol.(b), (2005). For single crystal CVD diamond: A.A.Kaminskii, R.J. Hemley, et al. Laser Phys. Lett. (2007). Stokes and anti-Stokes lines. SRS intensity comparable to pump

  17. Wavelength conversion range achieved experimentally polycrystalline CVD diamond Single crystal are more efficient. Raman laser on SC CVD diamond: R. Mildren et al. Opt. Lett. (2009) Excitation wavelengths: 0.53 μm, 1.06 μm, 1.32 μm Pulse duration: 15 ns, 10 ps and 80 ps. Yellowemissionat 573 nm; 5 kHz (ns), 1.2 W output power; conversion efficiency of 63.5%. 2.2 W with ps pulses (2010) Latest result: A continuous-wave (cw) operation of a diamond Raman laser at 1240 nm with power 10.1 W. A. McKay et al. Laser Phys. Lett., 10 (2013)105801.

  18. Commercial SRS-active crystalline materials with laser frequency shift (ωSRS) more than 850 cm-1 A.A. Kaminskii, Laser Physics Letters, 3 (2006) 171.

  19. Diamond Raman laser Institute of Photonics, University of Strathclyde, UK Industrial Diamond Rev. No. 4, 2008.

  20. C. Wild, SMSA 2008, Nizhny Novgorod

  21. Diamond window for IR cw lasers CVD diamond, 25 mm diameter, 1.2 mm thickness Modeling: radial temperature profile ANSYS program, finite element analysis. ● all absorbed heat dissipates via cooled edges. ●Laser parameters: beam diameter 10 mm; incident power 5.0 kW; absorption coeff. =0,1см-1 (at 10.6 μm). Result - heating ΔT<9°C. Experiment: Exposed to a fiber Nd:YAGcw laser for 1 min; power 10.0 kW, beam diameter 5 mm, Result - window survived V.E. Rogalin et al. Russian Microelectronics, 41 (2012) 26.

  22. Gyrotrons – generators of powerful mm waves (~100-200 GHz) Requirements to gyrotron window material:  very low absorption (low loss tangent)  high mechanical strength (Young’s modulus, E)  low dielectric permittivity, .  low thermal expansion coefficient,   high thermal conductivity, k, **DeBeers sample [V. Parshin et al. Proc. 10th Int. ITG-Conf. on Displays and Vacuum Electronics, 2004] Properties of some materials important for mm-waves windows (T=293 K and f=145 GHz) *Diagascrown/GPI sample [B. Garin et al. Techn. Phys. Lett. 25 (1999) 288] **DeBeers sample [V. Parshin et al. Proc. 10th Int. ITG-Conf. on Displays and Vacuum Electronics, 2004

  23. Vacuum-tight CVD diamond windows brazed to copper cuffs TESTS Thermal cycling: ● 25-750-25C and (–60)-(+150)C ● 8 hours heating at 650C. No degradation in vacuum tightness. Window diameter 60 mm and 15 mm Loss tangent ~10-5. V. Parshin, 4th Int. Symp. Diamond Films and Relat. Mater., Kharkov, Ukraine, 1999, p. 343.

  24. CVD diamond to manage synchrotron radiation Synchrotrons generate extremely bright radiation by electrons orbiting in magnetic field with speed close to velocity of light. Photons in a broad IR to X-ray range; power density of hundreds W/mm2. Synchrotron Soleil, Paris Diamond instead of Si for: ● beam attenuators; ● fluorescent screen for beam monitoring; ● X-ray and UV detectors, ● monochromators (first tested at European Synchrotron, Grenoble, in 1992), (only single crystals appropriate) Water cooled IR window from Diamond Materials, Germany

  25. High transparency of diamond for X-rays can be utilized for making X-ray lenses Transmission of 0–20 keV radiation through 20 μm thick beryllium, diamond and silicon. C. Ribbing et al. Diamond Relat. Mater. 12 (2003) 1793.

  26. Principle of X-ray focusing by a refractive lens For X-rays refractive index n=1-δ, (δ<<1) ► a hole acts as the lens

  27. Refractive CVD diamond X-ray lens produced by molding technique Diamond films of ca. 110 m thickness Geometry of X-ray focusing test. X-ray diamond lenses of 15 x 40 mm2 size with relief depth of 100 and 200 μm. Four parabolic lenses are formed on each 110 μm thick diamond plate. Lens test at synchrotron (ESRF, Grenoble): Beam focusing at 2 μm diameter; focal distance 50 cm; lens gain: 22-100. X-ray transmission 80% @ 38 keV; X-ray power density 50 W/mm2 – long term (16 hours) stability (experiment); up to 500 W/mm2 – acceptable (simulation). A. Snigirev, Proc. SPIE, Vol. 4783 (2002) p. 1.

  28. CVD diamond anvils for high-pressure/high-temperature experiments CVD-based diamond anvils have strength that is at least comparable to and potentially higher than anvils made of natural diamond. Reparation of damaged anvil combined CVD-natural diamond anvil. The same anvil after removing of the polycrystalline material, reshaping, and polishing to anvil with 30μm in diameter of the center flat culet. CVD-covered anvil immediately after the growth. Test: successful HPHT measurements on hydrogen at megabar pressures. C.-S. Zha et al. High Pressure Research, 29 (2009) 317

  29. Opal (and inverse opal) as photonic crystal opal and inverse opal structures Silica opals are made by self-assembly of SiO2 spheres into face-centered cubic (fcc) crystals. The narrowest channel (pore) diameter ≤ 39 nm for balls of 250 mm diameter. Pores in opal lattice can be filled with other materials to make a composite or inverse structure (replica). A.A. Zakhidov, Science, 282 (1998) 897.

  30. Diamond inverse opal produced by replica technique Seeding with ND partciles, diamond deposition in microwave plasma A.A. Zakhidov, Science, 282 (1998) 897.

  31. Inverted opal made of amorphous Si Produced at A. IoffePhys.Technical Inst. RAS, St. Petersburg Thermal decomposition of SiH4 in pores of SiO2 opal, followed by SiO2 matrix etching. Inverted Si opal – porous structure Seeding with ND Period 310 nm, pore diameter ~100 nm. Plate thickness 400 µm.

  32. Direct opal diamond L = 310 nm, 25 layers of spheres Next step: diamond deposition in Si opal template followed by the Si etching. A lot of a-C and graphite in the deposit. Graphite etching by oxidation in air at Т = 500ºС. Raman spectra excited in UV (244 nm), top, and in the visible (488 nm), bottom,regions Diamond opal. Cross section 10 µm below the growth surface. Clear diamond peak at 1332 cm-1 in UV. Still graphite-like is present. Sovyk D. N. et al. Physics of the solid state. 55 (2013) 1120.

  33. Diamond opal as photonic crystal Reflection spectra from inversed Si opal (period 310 nm) and direct diamond opal (period 260 nm) at angle 11° to (111) plane. Bragg reflection peaks are clearly observed. Si inversed opal D-opal Diamond shells (20 nm thick) with nanographitepartciles inside.(111) face.

  34. Conclusions • ● Polycrystalline diamond films and single crystals of high purity and large size can be produced by CVD technique. • ● The properties of CVD diamond approach (in some cases exceed) those known for the best natural single crystal diamonds. • ● Potential application of the CVD diamond include, in particular: -- detectors of ionizing radiation; • - X-ray, optics, IR and microwave optics for CO2 lasers, gyrotrons, etc; • - radiation-hard, high-temperature, high-power electronic devices; • - Raman lasers • -GHz-range devices based on surface acoustics waves; • -- new applications…

  35. GPI Diamond Materials Lab

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