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Applications of diamond films

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1 Applications of diamond films
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: 4.6 х 0.9 х 0.5 мм 8.6 х 1.4 х 0.5 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 Charge collection distance
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 µm present 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 SC CVD diamond UV detectors
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) La fotocnducibilità spettrale è stata per molto tempo, e anche oggi, la tecnica con la quale “vedere” la densità degli stati nella gap. Uno degli ultimi monocristalli avuti che mostra un rapporto Sopra-Gap/Sotto-Gap della responsivity di 6 ordini di grandezza. In genere la fotoconducibilità è fortemente dipendente dalla tensione applicata. In questo caso satura a valori molto bassi (5V/um), indicando un ottimo materiale! b) Confronto con un campione “Detector Grade” di Element Six. Sebbene il recovery di fotoconducibilità sia praticamente uguale, la coda di Urbach (dovuta alle variazione termiche della lunghezza e angolo di rotazione del legame diedrico (C-C), è più piccola: indica un materiale, almeno in questo caso, migliore. c) La foto mostra il campione A010 all’interno dell’holder utilizzato per le misure di fotoconducibilità. Da tenere presente che ANCHE i campioni monocristallini epitassiali, dopo la separazione dal substrato HPHT, vengono politi meccanicamente! The recovery of photoconductivity is more than 6 orders of magnitude and saturates around 5 V/µm. Low surface recombination and small Urbach tail.

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 UV, X-ray Source Imaging by 2D detectors
Past 36-pixel array (0.75 × 0.75 mm2) Poly 1 cm2 RAS 270 um Contacts – Ag nm Cu-Ka, 8.05 keV ArF 193 nm, 3 mW Uno dei dispositivi 2D realizzati su policristallo RAS. Si tratta di una matrice con contatti in Ag da 0.75x0.75 um2. E’ stata sviluppata anche l’elettronica di lettura, a integrazione veloce, con presentazione dei dati in tempo reale su monitor. a) Si mostra la risposta 2D e 3D, di un fascio di raggi X per diffrattometria, spostando il rivelatore. b) Risposta 3D, in tempo reale, della distribuzione di intensità di una laser a eccimero ArF. 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)

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 Shallow hydrogen induced acceptors.
p-type conductivity on H-terminated diamond surface: 2D hole layer (111) Surface with C-H bonds Microwave plasma H diamond H-terminated layer 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 cm2/Vs ♦ activation energy meV 1994: H-terminated diamond based FET H. Kawarada, et al., Appl. Phys. Lett. 65 less than 6 nm Hole density is evaluated from C-V characteristics G. Conte et al, NGC 2011, Moscow

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

13 MESFET frequency characteristics
Surface Channel MESFETs Past MESFET frequency characteristics Polycrystalline Diamond RAS PolyD4 Single Crystal Diamond RAS P7MS Wg=50 μm fMAX =26.3 GHz fT = 13.2 GHz Gain = 22 1 GHz fMAX/fT=1.8 WG=25 μm -20 dB/dec. Gain = 15 1 GHz fMAX = 23.7 GHz fT = 6.9 GHz Andamento del guadagno al variare della frequenza di due MESFET con canale da 200 nm e differente lunghezza. Su policristallo è stata misurata una frequenza massima di oscillazione di 23.7 GHz, con frequenza di taglio a 6.9 GHz. Su monocristallo I valori sono stati leggermente migliori. La deviazione della pendenza da -20 dB/dec della curva blu (MAG: Maximum Available Gain) è dovuta a instabilità della costante di Rollet. In ogni modo alla taglio la pendenza è quella corretta per un funzionamento in classe A. fMAX/fT=3.5 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)

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. K is R0= 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 use Stimulated Raman Scattering (SRS)
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: μm, 1.06 μm, 1.32 μm Pulse duration: 15 ns, 10 ps and 80 ps. Yellow emission at 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)

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. =0,1 см-1 (at 10.6 μm). Result - heating ΔT<9°C. Experiment: Exposed to a fiber Nd:YAG cw 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 Properties of some materials important for mm-waves windows
Gyrotrons – generators of powerful mm waves (~ 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) Material tan (10-4) k W/cmK 10-6 K-1 E GPa Fused quartz 3.8 3 0.014 0.5 73 BN 4.3 5 0.35 60 BeO 6.7 10 2.5 7.6 350 Sapphire 9.4 2 0.4 8.2 380 Au-doped Si 11.7 0.03 1.4 160 Diamond 5.7 0.08* 0.03** 20 0.8 1050 *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: ● 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: X-ray transmission 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 (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. Ioffe Phys.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 ● В спектре КР при возбуждении на λ = 488 нм проявляются линии как от алмаза (1334 cm -1), так и нанографита (1360, 1585 и 1623 cm-1) ● При возбуждении в УФ области (λ=244 nm) сечение КР для алмаза растет, его линия в спектре становится доминирующей. 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 nanographite partciles 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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