silicon and iii-v compounds for detectors – technology and...
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Silicon and III-V Compounds for Detectors – Technology and Characterisation at ITME
R. Kozlowski, Z. Luczynski and E. Nossarzewska-Orlowska
1st RD50 Workshop
(CERN, October 2-4, 2002)
Institute of Electronic Materials Technology, Warsaw, Polandwww.itme.edu.pl
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Plan of presentation
• short characteristic of ITME
• materials for detectors:
- silicon (bulk and epitaxial)
- III-V compounds (SI GaAs, SI InP and MOCVD III-V including GaN layers)
• materials characterisation methods
1st RD50 Workshop
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1st RD50 Workshop
The Institute consists of the following divisions:
• Department of Silicon Technology• Silicon Epitaxy Laboratory • Department of Semiconductor Compounds Technology• III-V Materials Epitaxy Laboratory• Department of III-V Materials Applications• Department of Oxide Single Crystals Technology• Department of Ceramics and Seals Technology• Laser Laboratory• Glass Laboratory• Department of Thick Films Technology• Department of Piezoelectronics• Laboratory of Characterization of High Purity Materials• Department of Microstructural Analyses
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1st RD50 Workshop
Czochralski silicon crystals
Orientations <111>, <100> and <110>Carbon content: max. 0.5 ppmOxygen content: controlled level in the range of 24-38 ppm
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1st RD50 Workshop
Silicon wafers -as cut, lapped, etched and polished
Available resources:• Thermal donors annealing furnace,• Silicon oxidation furnace (quartz tube up to 8”)
• Diameter: 76 mm, 100 mm, 125 mm, 150 mm (6”),• Orientation: <111>, <100> and <110>,• One-side or double-side polished,• Thin double-side polished wafers (down to 50 µm)
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1st RD50 Workshop
Float Zone silicon crystals
• diameter: 2”• orientation: <111> or <100>• doping:
- p-type: boron- n-type: phosphorus
• resistivity range:- boron: 20 - 300 Ωcm- phosphorus: 6 - 200 Ωcm
FZ silicon doped with different impurities for research purposes (Sn, O).
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Magnetic CZ puller*
• Better homogenity of the dope in axial and radial direction• Minimum available oxygen concentration: ~3x1017 at/cm3.
Magnet - 5000 GaussCharge capacity of the above: 30 kgDiameter of pulling crystals: 100 mmCable pulling system:Max pulling stroke: 1350 mm Seed pulling speed: 0.2 - 6.0 mm/minThe full automatic crystal growing control system.
* pulling will start in the beginning of 2003
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Si:Ga crystals (1)
Parameters of Ga doped silicon crystal:
Diameter – 3”Type – pResistivity – (0.5 –2.0) Ωcm[Ga] – (4x1016 – 7x1015) cm-3
[O] – 6.5x1017 cm-3
[C] < 5x1015 cm-3
The life time of minority carriers - 25÷30 µs.
A new generation of crystalline silicon solar cells
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Si:Ga crystals (2)1st RD50 Workshop
200 300 400 500 600
0.0
0.2
0.4
0.6
0.8
1.0
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1.8
2.0200 300 400 500 600
0.0
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1.6
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2.0
8-G
a6-G
a
4A+4B-Ga
3-G
a
B,P
1-Ga
T=11KA
bs. c
oeff.
(cm
-1)
Wavenumber (cm-1)
The absorption spectrum (FTIR) of Si:Ga related to the transition from the ground state to the exited states of gallium.
Line notification according to the paper: A.Onton et all., Phys.Rev. V 163 No 3, (1967), 685.
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Silicon epitaxial layers (1)1st RD50 Workshop
Epi-layer on substrates of diameter: 2”, 3”, 4”, 5”, 6” (CEMAT-Silicon)
Type n - phosphorus dopedType p - boron dopedThickness range: 1÷ 200 µmResistivity range: 0.01 ÷ 1000 ΩcmSingle layers and multi-layers structures
Characterization:thickness by IR reflectance spectrometry resistivity by: C-V method with Hg probe; spreading resistance(resistivity profile on a bevel), 4-points probe
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Silicon epitaxial layers (2)
Epitaxial layer thickness map measured on BIO-RAD spectrometer
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Silicon epitaxial layers (3)
Resistivity profile measured by SR method for high-resistivity
silicon epitaxial layer
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
0 10 20 30 40 50 60 70
micrometers
ohm
cm
Schematic view ofsilicon ball detector
A. Kordyasz et al..Nucl. Instr. andMeth. in Phys. Res A 390 (1997)
198-202
4π epitaxial Si detectors array for in-beam spectroscopy experiments
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Silicon epitaxial layers (4)Perspective material for thin silicon detectors
Resistivity profile of 50 µm, 50 Ωcm epitaxial layer
0.01
0.1
1
10
100
1000
0 20 40 60
w [ µm ]
Ro
[ o
hm
cm ]
Idea: the depletion voltage might stay constant up to very large fluences!
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Silicon epitaxial layers (5)1st RD50 Workshop
1.E-01
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
0 20 40 60 80 100
Thickness in depth [µm]
Res
isti
vity
[oh
mcm
]
Type "n"Type "p"
Epitaxial structure of integrated telescope E+∆E for identification of light charged particles and heavy ionsin nuclear and heavy ions physics
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III-V compounds (1)
GaAsØgrown by Czochralski (LEC) method (low and high-pressure)Ødiameter 2", 3" and 4", orientation <100> or <111>Øn-type : Te, Sn or Si (n=1017....1019 cm-3)Øp-type : Zn (n=1017....1019 cm-3)ØSemi-Insulating : undoped (µ > 6×103 cm2/Vs, ρ > 107 Ωcm).
InPØgrown by Czochralski (LEC) method Ødiameter 2", orientation <100> or <111>Øn-type : undoped (n=5×1015..1×1016cm-3)Øn-type : S, Sn (n=2×1017..1×1019cm-3)Øp-type : Zn (p=5×1017..1×1019cm-3)ØSemi-Insulating : Fe (µ > 2 x 103 cm2/Vs, ρ > 107 Ωcm )
Ingots
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III-V compounds (2)
Simplified structure of α particle detector based on SI GaAs or SI InP substrate
SI GaAs crystal parameters: µ>6000 cm2/Vs, ND<1015 cm-3, EPD<5x104 cm-2, homogeneity
The α particle detector
d = 100 µm
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1st RD50 Workshop
III-V compounds (3)
(a) (b)Spectra of α (228 Th) particle detected by SI GaAs detector. (a) structure illuminated from Schottky barrier side,(b) structure illuminated from ohmic contact side
The α particle detector
U=350 V U=350 V
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III-V compounds (4)
Charge collection efficiency for α- 5.48 MeV as a function of bias voltage for SI GaAs detector
0 100 200 300 400 500 6000
10
20
30
40
50
60
70
80
90
100
Cha
rge
Col
lect
ion
Effi
cien
cy
[%]
U [V]
The α particle detector
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III-V Materials Epitaxy Laboratory
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The growth of structures applying binary, ternary and quaternary compounds related to GaAs, InP
and GaN
EPITAXIAL LAYER THICKNESS:* from 1ML to 15µm;* radial thickness variation on the wafer: in the range of 1ML.
The following methods are used for the characterisation of layers:ØX-ray;ØPhotoluminescence;ØHall method;ØC-V profile with electrochemical etching;ØAtomic Force Microscopy.
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LP MOVPE - Low Pressure Metalorganic Vapor Phase Epitaxy
AXT 200 systemP=20÷100 mbarT= 650-700 oC
as III group elements:TMGa - trimethylgallium,TMIn - trimethylindium,TMAl - trimethylalumininum
as V group elements:AsH3 - arsinePH3 - phosphine
In Ga A P (=1,05(m (GRIN) d=80nm
In Ga A P (?=1,05?m) Si:7x10 cm (GRIN) d=80nm InP Si:3x10 cm ( buffer) d=1 ?m
InP n-type substrate
In Ga A P (?=1,18?m) Si:7x10 cm (GRIN) d=50nm In Ga A P (?=1,26?m) (barrier) d=12nm In Ga As (?=1,64?m) (active QW layer) d=8,5nm In Ga A P (?=1,26?m) (barrier) d=12nm In Ga A P (?=1,18?m) (GRIN) d=50nm
InP Zn:7x10 cm ( upper clading) d=500nm In Ga A P (?=1,05?m) (GRIN) d=80nm
In Ga A P (?=1,18?m) Zn:2x10 cm (contact) d=50nm In Ga As (?=1,64?m) Zn: 2x10 cm ( contact) d=100nm
Quantum well laser structure
as dopant:DMZn -dimethylzinkSiH4 - silane
Epitaxial layers: InP, GaAsand related materials
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LP MOVPE - Low Pressure Metalorganic Vapor Phase Epitaxy
AXT 200/4 RF-S systemP=100÷300 mbar
T= 1200 oC
as III group elements:TMGa - trimethylgallium,TMIn - trimethylindium,TMAl - trimethylalumininum
as V group elements:NH3 - ammonia
as dopant:Cp2MgSiH4
Epitaxial layers: GaN, AlN, AlGaN, InGaN
Applications: LEDs, HEMTs, lasers, photodetectors
Substrates: sapphire, NGO, Si, SiC and GaN (homoepitaxy)
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Substrate materials for GaN at ITME
MIXED PEROVSKITE − (La, Sr) (Al, Ta) O3 − LSATØCrystal system: regular (mixed
perovskite)Ø Lattice constant: a = 7.735 ÅØ Lattice mismatch: ∆ < 1%
NEODYMIUM GALLATE − NdGaO3Ø Crystal system: orthorombicØ Lattice constants: a = 5.4276 Å
b = 5.4979Åc = 7.7078Å
Ø Lattice mismatch : ∆ ~ 0,7% (101)
SAPPHIRE − Al2O3Ø Crystal system: trigonalØ Lattice constants: a = b = 4.7589 Å
c = 12.991 ÅØ Lattice mismatch: ∆ ∼14%
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1st RD50 Workshop
Processing department and mask laboratory (1)Technological line consists of:• deep UV optical lithography (0.5µm smallest feature size), • reactive ion etching (RIE) technique (and ICP type of RIE), • plasma enhancement chemical vapour deposition reactor(PECVD),
• RF/DC sputtering unit,• Rapid Thermal Annealing (RTA),• Ion Implantation.
Deposition of:• dielectrics ( Si3N4 SiO2, Al2O3, Y2O3),• semiconductors (AlN, GaN), • multilayer metal sandwiches.
Chromium masks on up to 7” substrates (smallest line width of 0.5µm)
Devices with sub micrometer geometry approaching quantum regime of operation (using e-beam writer).
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Electron-Beam lithography
Main fields of applications:
• fabrication of master masks and reticles for contact, proximity and projection lithography, especially for large area structures, like nuclear radiation detectorsor SAW filters and resonators
• direct exposure of semiconductor wafers, especially to be used in the sub-0.5-micrometer range (e.g. monolithic microwave integrated circuits, diffractive optical elements)
Processing department and mask laboratory (2)
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Electron-Beam lithography• high resolution and quality
Split gate 0.07 µmLift-off metallization Au/Cr 0.1 µm
Submicron strip structureLift-off metallization, line width 0.8 µm
• special 3D structures
The 0.2 µm footprint T-shaped gateLift-off metallization Au/Cr 0.4 µm
Central part of the 8-phase-levelFresnel microlens
Processing department and mask laboratory (3)
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Sensor of ultraviolet radiation on Gallium Nitride
• Absorption edge - 365 nm.• Detector exhibits high sensitivity only in the UV
range without applying expensive optical filters.• Sensitivity is 3 orders of magnitude lower for
visible light.
Processing department and mask laboratory (3)
280 300 320 340 360 380 400 420 440 4601E-4
1E-3
0.01
0.1
curr
ent s
ensi
tivity
( A
/ W
)
wavelenght ( nm )
Øactive surface 0.8 mm
Øcurrent sensitivity > 0.07 A/W
Ødetectivity D > 109 cm Hz1/2/W
Ødynamic resistivity (U = 0) 10 GΩ
ØUV/visible light rejection ratio > 103
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• C-V and S-R,
• FTIR spectrometer,
• photoluminescence,
• SIMS (Cameca IMS 6F)
• electron micro-probe analysis (Cameca SX100),
• HRPITS and C-DLTS,
• ESR
Materials characterisation methods at ITME:
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1st RD50 Workshop1st RD50 Workshop
SIMS
SIMS profile of O-concentration for silicon sample,O-diffusion: 16 hrs at 1150 oC
(Measurement on bevelled sample)
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1st RD50 Workshop
ESR
ESR spectra of Mn2+ in GaN crystal
220 240 260 280 300 320 340 360 380 400 420 440 460
band X, T = 6 K
GaN: MnH || c
ES
R s
igna
l [ar
b.u.
]
magnetic field [mT]
In GaN crystals Mn2+ have 3d5 electron configuration wit S=5/2. Therefore in EPR spectra we observe 5 fine structure lines. Each of them is splitted on six components. This splitting is caused by hiperfine interaction between electron spin and magnetic nucleus 55Mn with nuclear spin I=5/2
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700 800 900 1000 1100 1200 1300
0.6
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1.0
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1.4
1.6700 800 900 1000 1100 1200 1300
0.6
0.8
1.0
1.2
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TDD
3
VnO
m
TDD
3
VO
3
VO
2
b)VO
3
1225
VO
3TD
D3
a)
OiT=300K
Abs
orpt
ion
coef
ficie
nt (
cm-1
)
Wavenumber (cm-1)10
12TD
D3
The local vibration modes of VnOn defects in:a) neutron irradiated with dose 6x1016n/cm2; b) non-irradiated silicon after annealing at 600 oC
FTIR
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Summary1st RD50 Workshop
• ITME activities in silicon technology were exemplified trough the wide range of parameters of silicon ingots, wafers and epitaxial layers.
• Research and development works in the field of III-V compounds comprise the growth of bulk crystals (in particular SI GaAs and SI InP) and deposition of multilayered structures.
• ITME recent activities in technology of wide-bandgapmaterials are related both with the preparation of substrates and MOCVD epitaxial growth of GaN structures.
• The ITME facilities for fabrication of semiconductor devices and materials characterisation were also outlined.
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