CVD Diamond

Report
Lecture 5
Applications of diamond films
CVD diamond devices and components
microwave transistor
on diamond wafer
IR windows for
gyrotron and CO2 lasers
Cutting tools
UV and X-ray detectors
thin membranes
X-ray lenses and screens
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
Thin diamond films on AlN ceramics
V.G. Ralchenko, Russian Microelectronics, 2006, Vol. 35, No. 4, p. 205.
AlN before diamond ►
deposition
◄ Coated with black
diamond
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.
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
CVD diamond UV detectors
solar-blind photoresistors
Photoresponse of nucleation (1) and growth sides
10
Responsivity (A/W)
1
0,1
0,01
1E-3
1E-4
2
1E-5
1E-6
1
1E-7
1E-8
0
200
400
600
800
1000
1200
Wavelength (nm)
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.
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)
0
10
-1
10
-2
10
-3
10
RAS SC A010
3
10
-4
10
-5
10
-6
10
-7
10
-8
4.8x4.8x0,49 mm
=4.1 nm
Ag 40 m grid
Responsivity (A/W)
Responsivity (A/W)
10
38±5 meV
100V
0
10
-1
10
-2
10
-3
10
-4
10
-5
10
-6
10
-7
10
-8
Eg
RAS SC A010
=4.1 nm
Ag 40 m grid
200V
E6 SC-DG
50±5 meV
38±5 meV
200V
2
3
4
5
6
7
Photon Energy (eV)
The recovery of photoconductivity is more
than 6 orders of magnitude and saturates
around 5 V/µm.
2
3
4
5
6
Photon Energy (eV)
Low surface recombination and
small Urbach tail.
7
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
Sensor electronics
on two sides of the diamond sample.
0,4
5
4
3
0,2
2
0
0
2
4
6
8
Scan direction (mm)
mm2
Output signal : 1
beam illuminates the
pixels along the row direction.
1
9
8
7
6
5
4
3
2
1
2
5
3
4
4
x (m
5
m)
3
6
7
2
81
Colonne (x)
incident
6
measured
Test monochromatic beam profile
7
8
)
6
0,6
Righe (y)
Amplitude
V out (mV)
7
0,8
m
8
m
1
26
24
22
0
20
18 4,167
16
8,333
14
1212,50
10
16,67
8
620,83
4
25,00
2
0
1
y(
9
Past
UV, X-ray Source Imaging
UV, X-ray Source Imaging by 2D detectors
•
•
•
•
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
S6
S5
S4
S3
S2
S1
1
X-ray tube beam profile when scanned across
the detector
2
3
4
5
6
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.
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.
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
carriersmodel”.
density value 1013
•cm
Shallow
hydrogen induced
-2
♦ acceptors.
hole mobility 100-130
1994:
H-terminated diamond based FET
2
cm
/Vs
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
♦ activation energy 1.6-4.1
meV
Device Technology Issues
Device Layout
MESFET technology issues
Batterfy-shaped design
25 μm ≤ WG ≤ 200 μm
0.2 μm ≤ LG ≤ 1 μm
Drain
(Au)
Small H-terminated area for leakage current reduction and
electric field confinement.
WG
Source
(Au)
CVD Diamond
Gate
(Al)
Source
(Au)
2D Hole Channel
Surface Channel MESFETs
Past
MESFET frequency characteristics
Polycrystalline Diamond
RAS PolyD4
Single Crystal Diamond
RAS P7MS
40
40
WG=25 μm
30
Wg=50 μm
-20 dB/dec.
30
Gain = 22 dB @ 1 GHz
20
fMAX = 23.7 GHz
10
M A G [dB ]
G ain (d B )
G a in (d B )
Gain = 15 dB@ 1 GHz
20
fMAX =26.3 GHz
10
2
2
|H | [d B ]
|H | [dB ]
21
21
0
0
fT = 6.9 GHz
-10
0,1
M A G [d B ]
1
fT = 13.2 GHz
fMAX/fT=3.5
10
10 0
-10
0,1
10
F req u en cy (G H z)
F req u en cy (G H z)
Eapplied= 0.5 MV/cm
1
fMAX/fT=1.8
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.
10 0
Fast CVD diamond bolometer
Very thin buried graphitized layer as resistor.
Fast dissipation of absorbed energy – quick response.
la ser bea m
2
2
1
gra
p h it
e
d ia m o nd
1- buried graphite; 2 - contacts
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
T.I. Galkina, Physics of Solid State (St. Petersburg), 49 (2007) 621.
Test of diamond bolometer
Pulsed irradiation with a nitrogen laser (λ=337 nm, τ~ 8 ns).
Beam spot size 90 μm.
Normalized respenses, a.u.
0.0
R

c1 1 1 
-0.2
1
c2 22 2
-0.4
c3 33 3
-0.6
0
L1
0
L2
0
L3
z
r
G1
G2
Layered structure for
simulation of the bolometer
response kinetics.
-0.8
-1.0

0
20
40
60
Time, ns
80
100
Measured signal (circles) and modeling (solid line).
Response signal ≈20 ns (FWHM), very fast for bolometer-type sensors
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.
pum p
9
8
L o g in te n s ity
7
6
5
4
S to ke s
3
2
a n ti-S to ke s
1
0
 - 
0

1
 + 
0
0
1
excitation at λ=1.06 µm;
three anti-Stokes lines
stimulated RS
pum p
S t1
A S t1
S t2
 - 2
0
A S t2
1
 - 
0
1

0
 + 
0
1
 + 2
0
1
Stokes and anti-Stokes lines.
SRS intensity comparable to pump
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).
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)
T ra n s m itta n c e , %
80
60
0 .4 6 6  m
2 .0 3 3  m
40
20
0
0 ,1
1
10
W a ve le n g th ,  m
Excitation wavelengths: 0.53 μm, 1.06 μm, 1.32 μm
Pulse duration: 15 ns, 10 ps and 80 ps.
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.
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)
Commercial SRS-active crystalline materials with
laser frequency shift (ωSRS) more than 850 cm-1
Crystal
Lithium formate
LiHCOO·H2O
natural diamond
CVD diamond
Calcium carbonate
CaCO3
Sodium nitrate NaNO3
Barium nitrate Ba(NO3)2
Potassium yttrium
tungstate KY(WO4)2
Lead tangstate PbWO4
Yttrium vanadate YVO4
Shift
(cm-1)
1372
Gain
Phonon
Reference
(cm/GW) lifetime (ps)
3
10
K. Lai, Phys. Rev. B (1990).
1332
1332.5
15
>11
5
4.2
1086
1.6
8.3
A. McQuillan, Phys. Rev. A (1970).
A. Kaminskii,
Laser Phys. Lett. (2006)
G. Pasmanic, LFW, Nov 1999
1059
1040
905
7
10
3.6
10
26
1.5
G. Pasmanic, LFW, Nov 1999
A. Eremenko, Kvant.Electron. (1980)
A. Ivanyuk, Opt. Spectrosc. (1985)
1.5
3.5
A. Kaminskii, Opt. Commun. (2000)
A. Kaminskii, Opt. Commun. (2001)
901
890
Diamond, having highest gain, can be the next commercial crystalline medium for Raman shifters.
A.A. Kaminskii, Laser Physics Letters, 3 (2006) 171.
Diamond Raman laser
Institute of Photonics, University of Strathclyde, UK
Industrial Diamond Rev. No. 4, 2008.
C. Wild, SMSA 2008, Nizhny Novgorod
Diamond window for IR cw lasers
CVD diamond, 25 mm diameter, 1.2 mm thickness
d=5x2mm k=18W/cm*K P=5KW
34
, cm
0
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.
-1
0,03
0,06
0,1
32
T ( C)
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.
Modeling: radial temperature
profile
30
28
26
-15
-10
-5
0
5
Distance from center (mm)
10
15
Gyrotrons – generators of powerful mm waves (~100-200 GHz)
Requirements to gyrotron window material:
 very low absorption (low loss tangent)
 low dielectric permittivity, .
 high thermal conductivity, k,
 high mechanical strength (Young’s modulus, E)
 low thermal expansion coefficient, 
**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)

tan
(10-4)
k
W/cmK

10-6 K-1
Fused quartz
3.8
3
0.014
0.5
73
BN
4.3
5
0.35
3
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
2.5
160
Diamond
5.7
0.08*
0.03**
20
0.8
1050
Material
E
GPa
*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
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.
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
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.
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
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.
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.
CVD-covered anvil immediately
after the growth.
The same anvil after removing of the
polycrystalline material, reshaping, and
polishing to anvil with 30μm in diameter of
the center flat culet.
Test: successful HPHT measurements on hydrogen at megabar pressures.
C.-S. Zha et al. High Pressure Research, 29 (2009) 317
Opal (and inverse opal) as photonic crystal
opal and inverse opal structures
Silica opals are made by selfassembly of SiO2 spheres into facecentered 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.
Diamond inverse opal produced by replica technique
Seeding with ND partciles, diamond deposition in microwave plasma
A.A. Zakhidov, Science, 282 (1998) 897.
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
Period 310 nm, pore diameter ~100 nm.
Plate thickness 400 µm.
Seeding with ND
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
1336 cm-1
25
1585 cm-1
Intensity, a.u.
20
15
1360 cm-1
10
1585 cm-1
1334 cm-1
1623 cm-1
5
Diamond opal. Cross section 10 µm
below the growth surface.
ex=244 nm
0
ex=488 nm
1200
1300
1400
1500
Raman shift, cm
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.
1600
-1
1700
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.
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…
GPI Diamond Materials Lab

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