FORMATION, MORPHOLOGIES, COMPOSITION AND OPTOELECTRONIC PROPERTIES Vitali Parkhutik Department of...
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FORMATION, MORPHOLOGIES, FORMATION, MORPHOLOGIES, COMPOSITION AND OPTOELECTRONIC COMPOSITION AND OPTOELECTRONIC PROPERTIES PROPERTIES Vitali Parkhutik Department of Materials Science, Technical University of Valencia OUTLINE: Introduction Basics of p-Si growth Morphology and structure Chemical Composition Optical properties Electrical properties
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Transcript of FORMATION, MORPHOLOGIES, COMPOSITION AND OPTOELECTRONIC PROPERTIES Vitali Parkhutik Department of...
FORMATION, MORPHOLOGIES, FORMATION, MORPHOLOGIES, COMPOSITION AND OPTOELECTRONIC COMPOSITION AND OPTOELECTRONIC
PROPERTIESPROPERTIES
Vitali Parkhutik
Department of Materials Science, Technical University of Valencia
OUTLINE:
Introduction
Basics of p-Si growth
Morphology and structure
Chemical Composition
Optical properties
Electrical properties
P-Si IS AN INTERESTING RESEARCH ISSUEP-Si IS AN INTERESTING RESEARCH ISSUE
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NUMBER OF PUBLICATIONS
Years
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
STRUCTURE AND BAND DIAGRAMSTRUCTURE AND BAND DIAGRAM
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
SET-UP FOR p-Si GROWTHSET-UP FOR p-Si GROWTH
0 200 400 600 800 1000 12000.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
n+-Si (100), 30 mA/cm
2
An
od
ic V
olt
ag
e,
V (
vs
.Pt)
Time, s
1 part of 48% HF + 1 part of ethanol
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
ALL THIS IS THE POROUS SILICON ALL THIS IS THE POROUS SILICON
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
Pore width, nm Type of pore
2
2-50
>50
Micro
Meso
Macro
Why p-Si is interesting? Why p-Si is interesting?
1. Fundamental theoretical background
1.1. Physics of bulk semicon- ductors and nanocrystals
1.2. Electrochemistry of semi-conductors
1.3. Electrical transport in non-ordered materials
1.4. Optical properties of nano-clustered semiconductors
2. Laboratory training
2.4. Electrical properties of porous silicon (dc and ac conductivity)
3. Applications
3.2.Light-emitting devices
3.1. Stabilization of PS properties
3.3. Chemical sensors
3.4. Biological and medical monitoring
2.1. Formation of porous silicon layers
2.2. Chemical composition of porous silicon
2.3. Optical properties of porous silicon
1.5. Physics of non-lineal dynamic systems
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
Electrones or holes?Electrones or holes?
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
KINETICS OF Si POLARIZATION IN
WATER-CONTAINING ELECTROLYTES
P-Si growth
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
DETERMINATION OF POROSITY
1. Gravimetric method
M0 – Mass of Si sample before anodizingM1 – Mass of Si sample after anodizingM2 – Mass of Si sample after removal pSi layer
20
10
MM
MM
IntroductionBasics growthMorphologyCompositionElectrical Optical
POROSITY OF p-Si INCREASES WITH THE ANODIC
CURRENT DENSITY
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
Current density alters the type of porosity
Ja=10 mA/cm2
Ja=30 mA/cm2
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
PORE RADIUS INCREASES WITH
THE ANODIC CURRENT DENSITY
25% HF, 10(1), 80 (2) and 250 mA/cm2 (3)
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
OUDULATING MACRO-PORES ARE PRODUCED
BY PERIODIC CHANGE OF CURENT DESNITY
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
Doping Etching rateIllumination
during etching
n+
p+
p or n
p
n
Very high
High
Medium
Low
Very low
No influence
No influence
Illuminated
Dark
Dark
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
DOPING LEVEL INFLUENCES THE p-Si
GROWTH RATE AND STRUCTURE
FACTORS INFLUENCING THE p-Si GROWTH:
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
- anodic current density,
- HF concentration,
- Si doping level,
- illumination
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
PORE DIRECTIONS ARE FOLLOWING THE CRYSTALLOGRAPHY OF Si WAFER
Highly ordered macro-p-SiHighly ordered macro-p-Si
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
Nanowires of Si preserve the crystallinity of
bulk Si
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
Size of Si clusters can be determined through fitting Raman scattering data
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
Chemical Composition of p-SiChemical Composition of p-Si
SiHx (x=1,2,3)
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
SiOx
A.c. conductivity of p-SiA.c. conductivity of p-Si
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
Reflection of light from p-Si Reflection of light from p-Si
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
OPTICAL ABSORPTION IN p-Si
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
Photoluminescence of p-Si
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
Confinement effects in Si clustersConfinement effects in Si clusters
IntroductionBasics growthMorphologyCompositionElectrical Prop.Optical Prop.
