Dr. Mirabella Salvatore
Consiglio Nazionale delle
Ricerche - Istituto per la
Microelettronica e Microsistemi,
Università d...
SALVO MIRABELLA
CATANIA, ITALY
THE KEY ROLE OF SURFACE IN
SEMICONDUCTOR NANOSTRUCTURES FOR
PHOTOVOLTAICS AND SENSING APPLI...
Catania
J. DANCKERTS, XVII sec.
04 Dec. 2015
www.matis.imm.cnr.it
Nanostructures
1434
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 4/44
Laurie McCormik
Nanostructures
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 5/44
OUTLINE
0D
1D
2D
Ge QDs: not only size matters
ZnO...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 6/44
OUTLINE
0D
1D
2D
Ge QDs: not only size matters
ZnO...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 7/44
Ge QDs for PV
Ge vs. Si
• Higher absorption coeffi...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 8/44
Light absorption in Ge QDs
S. Cosentino et al. APL...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 9/44
Light absorption in Ge QDs
1 2 3 4 5
10-19
10-18
1...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 10/44
Optical bandgap variation
2 4 6 8 10
1.0
1.5
2.0
...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 11/44
2 nm
Ge QD
TEM analysis
Z contrast profiling reve...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 12/44
EELS-STEM analysis
0.0
0.2
0.4
0.6
0.8
1.0
5 10 1...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 13/44
SPDEM model
E. G. Barbagiovanni, et al., J. Appl....
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 14/44
Interface effect on bandgap
2 4 6 8 10
1.0
1.5
2....
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 15/44
Ge QDs - conclusion
0D
Ge QDs: not only size matt...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 16/44
OUTLINE
0D
1D
2D
Ge QDs: not only size matters
Zn...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 17/44
Global connections
Exponential growth of devices ...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 18/44
Sensors invasion
Need for low-cost, massive
and c...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 19/44
OUTLINE
0D
1D
2D
Ge QDs: not only size matters
Zn...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 20/44
Step One
Seed Layer
Zinc Acetate
in ethanol
Spin ...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 21/44
ZnO NRs: HMTA effect
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 22/44
ZnO NRs: HMTA effect
V. Strano, et al., J. Phys. ...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 23/44
Laser irradiation of ZnO NRs
Adrian M. Chitu, pro...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 24/44
Laser irradiation of ZnO NRs
580 mJ/cm2
310 mJ/cm...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 25/44
ZnO NRs and light
Below gap light
Above gap light...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 26/44
ZnO NRs: light emission
Near band edge emission: ...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 27/44
Defect engineering
ERDA
H detection
PLE
Visible P...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 28/44
BGOR model
E. G. Barbagiovanni, et al., Nanoscale...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 29/44
ZnO NRs: UV sensing
E. G. Barbagiovanni, et al., ...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 30/44
ZnO NRs - conclusion
1D
ZnO NRS: surface defect e...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 31/44
OUTLINE
0D
1D
2D
Ge QDs: not only size matters
Zn...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 32/44
ZnO nanowalls
Growth
upon Al film
90°C, 1h Aqueou...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 33/44
ZnO NWs: growth
Al(OH)4
-
Al(OH)4
-
Al(OH)4
-
Sub...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 34/44
• Al/ZnO nanoporous provides a perfect
conducting...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 35/44
pH sensor
Basic test for further biosensors (as
E...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 36/44
Future glucose sensor
Today  Tomorrow
Less inva...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 37/44
Non-enzymatic glucose sensing
Issues with non-enz...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 38/44
Chemical bath deposition
Ingredients:
1) Nickel s...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 39/44
30 35 40 45 50 55
Ni (211)
Ni (200)
Ar90FG60
FG60...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 40/44
Glucose sensor
CV (0 – 0.8 V vs SCE)
30 cycles, a...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 41/44
Glucose sensor tests
0 100 200
0.0
0.3
0.6
0.9
1....
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 42/44
2D - conclusion
2D
ZnO NWs: flexible pH sensor
Ni...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 43/44
Acknowledgements
0D
1D
2D
Post-doc & PhD: S Cosen...
Columbia University, MSE colloquium, New York mirabella@ct.infn.it 44/44
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The key role of surface in semiconductor nanostructures for photovoltaics and sensing applications

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Seminar given at Columbia University - APAM Dept. - held on 11 December 2015.
The key role of surface defects in 0D, 1D, 2D nanostructures is discussed, for applications in energy conversion and sensing area. Some flexible devices based on low-cost nanostructures are also presented, as pH sensor and glucose sensor.

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The key role of surface in semiconductor nanostructures for photovoltaics and sensing applications

  1. 1. Dr. Mirabella Salvatore Consiglio Nazionale delle Ricerche - Istituto per la Microelettronica e Microsistemi, Università di Catania, Dip. Fisica e Astronomia, Catania, Italy Hosted by Prof. Barmak The key role of surface in semiconductor nanostructures for photovoltaics and sensing applications In the current nanotechnology age a countless amount of “small and smart” solutions are investigated and proposed in real devices for a variety of applications, such as photovoltaics, sensing, catalysis, security, environment, biomedical area ... The exploitation of nanostructures (NS) usually benefits from enhanced surface over volume ratio and from quantum confined effects arising at the nanoscale. Still, surface states and interface defects quite often overwhelm the previous effects and ask to be comprehended in details for a full utilization of NS. In this talk I’ll give few examples of surface/interface effects in semiconductor NS (Si and Ge QDs, ZnO and NiO low-cost NS) applied to photovoltaics and sensing. The light absorption in Si and Ge NS embedded in insulators will be presented, evidencing whether and to which extent the quantum confinement effect influences the light-matter interaction. An ideal size tuning of the optical bandgap is achieved only if Ge quantum dots have thin and defect-free Ge/SiO2 interface. Indeed, an unprecedented high absorption efficiency, ten times larger than in the bulk, is obtained for smaller and well-ordered Ge QDs in a superlattice approach. Despite the huge potential in disposable sensors, low-cost NS of transition metal oxides (TMO) often lack reproducibility and stability because of the growth method. The growth mechanism of ZnO nanorods and nanowalls by means of chemical bath deposition will be presented and modeled, as well as the surface states responsible for UV- and pH- sensing will be evidenced. Finally, a facile synthesis on plastic substrate of a large surface area, NiO NS will be described and applied as a high sensitivity, non enzymatic glucose sensor. Friday, December 11, 2015 11:00 a.m. Room 214 S. W. Mudd
  2. 2. SALVO MIRABELLA CATANIA, ITALY THE KEY ROLE OF SURFACE IN SEMICONDUCTOR NANOSTRUCTURES FOR PHOTOVOLTAICS AND SENSING APPLICATIONS
  3. 3. Catania J. DANCKERTS, XVII sec. 04 Dec. 2015
  4. 4. www.matis.imm.cnr.it Nanostructures 1434
  5. 5. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 4/44 Laurie McCormik Nanostructures
  6. 6. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 5/44 OUTLINE 0D 1D 2D Ge QDs: not only size matters ZnO NRs: surface defect engineering ZnO NWs: flexible pH sensor NiO NF: flexible glucose sensor
  7. 7. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 6/44 OUTLINE 0D 1D 2D Ge QDs: not only size matters ZnO NRS: surface defect engineering ZnO NWs: flexible pH sensor NiO NF: flexible glucose sensor
  8. 8. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 7/44 Ge QDs for PV Ge vs. Si • Higher absorption coefficient • Larger size range for QCE • Bandgap tuning within solar spectrum Si QDs Ge QDs Multi-junction SC All Si tandem solar cell “dream”
  9. 9. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 8/44 Light absorption in Ge QDs S. Cosentino et al. APL (2011) P. Liu et al. JAP (2012) S. Mirabella et al. APL (2012) S. Cosentino et al. NRL (2013) S. Mirabella et al. APL (2013) S. Cosentino et al. JAP (2014) S. Cosentino et al. SOLMAT (2015) E. Barbagiovanni et al., JAP (2015) S. Cosentino et al., Nanoscale (2015)
  10. 10. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 9/44 Light absorption in Ge QDs 1 2 3 4 5 10-19 10-18 10-17 PECVD QDs (3.5 nm) PECVD QDs (4.4 nm) Sputter QDs (3 nm) Sputter QDs (4 nm) Absorptioncrosssection[cm2 ] Energy [eV] • Blue shift with decreasing QD size • Greater shift in PECVD w.r.t. sputter D t ασ = • Ge QDs (2-8 nm) embedded in SiO2 • Ge QDs density (~ 1018 cm-3) • Surface to surface (S2S) distance (1-3 nm) absorption (α)  absorption cross section (σ): photon absorption probability per Ge dose SiGeO film PECVD or sputter (deposition 250°C: 8 - 20% Ge) (600-800°C annealing in N2)
  11. 11. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 10/44 Optical bandgap variation 2 4 6 8 10 1.0 1.5 2.0 2.5 3.0 QD size [nm] PECVD Sputter a-Ge bulk OpticalBandgap[eV] 2 4 6 8 10 1.0 1.5 2.0 2.5 3.0 QD size [nm] PECVD Sputter a-Ge bulk OpticalBandgap[eV] • Eg vs size depends on synthesis technique … • Is there any role of interface ? ( ) ( )2opt g Tauc E B −⋅= ω ω ωα   Tauc law VB CB VB CB Ge/SiO2 Ge/GeO2 V0,e 2.8 eV 1.2 eV V0,h 4.5 eV 3.6 eV 2 4 6 8 10 1.0 1.5 2.0 2.5 3.0 QD size [nm] PECVD Sputter a-Ge bulk EMA OpticalBandgap[eV] ( ) 2 0 *2* 22 2 1 2 )( −         +⋅+= VmrLm bulkEQDE gg π • Eg vs size depends on synthesis technique … • Is there any role of interface ? • Any difference in the interfaces ? SiO2 SiO2Ge QD SiO2 SiO2Ge QD GeO2
  12. 12. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 11/44 2 nm Ge QD TEM analysis Z contrast profiling reveals systematically thinner interfaces in PECVD samples 2 1)( 1)( 0 QDdiameter exf xx ≥Γ      += − Γ − − 3.5 nm QD
  13. 13. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 12/44 EELS-STEM analysis 0.0 0.2 0.4 0.6 0.8 1.0 5 10 15 20 25 30 35 40 45 50 55 60 0.0 0.2 0.4 0.6 0.8 1.0 Sputter Intensity[a.u.] PECVD Intensity[a.u.] Energy [eV] EELScore QD Fit interband transition Ge Ge QDvol. plasmon SiO2 vol. plasmon Ge-Ge M4,5 band Ge-OM4,5 band AGe-O AGe-Ge AGe-pl )( plGeGeGe OGe OGe AA A F −− − − + = FGe-O ~ 16 % for sputter FGe-O ~ 8 % for PECVD STEM: e-beam probe a cylinder of ~ 40 Ge atoms, 3 of which at surfaces • Significant Ge-O surface contribution • Greater Ge-O contribution in sputter samples • Thinner interface in PECVD samples e-beam • How to consider these interfaces features in the QCE of Eg variation ?
  14. 14. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 13/44 SPDEM model E. G. Barbagiovanni, et al., J. Appl. Phys. (2012), 111, 034307 E. G. Barbagiovanni, et al. Physica E, (2014), 63, 14–20 E. G. Barbagiovanni, et al., J. Appl. Phys. (2015), 117, 154304 Confining potential breaks the translational symmetry  new momentum operator (pγ) effective mass spatially dependent m(x)~1/(1+γx)2 γ~1/D as D decreases  m(x) decreases  confinement energy increases
  15. 15. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 14/44 Interface effect on bandgap 2 4 6 8 10 1.0 1.5 2.0 2.5 3.0 QD size [nm] PECVD Sputter a-Ge bulk OpticalBandgap[eV] 2 4 6 8 10 1.0 1.5 2.0 2.5 3.0 QD size [nm] PECVD Sputter a-Ge bulk EMA OpticalBandgap[eV] 2 4 6 8 10 1.0 1.5 2.0 2.5 3.0 QD size [nm] PECVD Sputter a-Ge bulk EMA SPDEMPECVD SPDEMSputter OpticalBandgap[eV] Ge/SiO2 Ge/GeO2 PECVD Sputter V0,e 2.8 eV 1.2 eV 1.1 eV 0.9 eV V0,h 4.5 eV 3.6 eV 3.3 eV 2.8 eV ( ) ( )         + ⋅ += * , , * , , 2 3 hc hc ec ecbulk gg m V m V DD EDE µ  SPDEM model well accounts for the different Eg variation in the two samples S. Cosentino, et al., Nanoscale (2015), 7, 11401 QD SPDEM model
  16. 16. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 15/44 Ge QDs - conclusion 0D Ge QDs: not only size matters  Interface states affect the quantum confinement  PECVD samples closer to ideal QCE (Ge/GeO2) E. G. Barbagiovanni, et al., J. Appl. Phys. (2015), 117, 154304 S. Cosentino, et al., Nanoscale (2015), 7, 11401 2 4 6 8 10 1.0 1.5 2.0 2.5 3.0 QD size [nm] PECVD Sputter a-Ge bulk EMA SPDEMPECVD SPDEMSputter OpticalBandgap[eV]
  17. 17. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 16/44 OUTLINE 0D 1D 2D Ge QDs: not only size matters ZnO NRS: surface defect engineering ZnO NWs: flexible pH sensor NiO NF: flexible glucose sensor
  18. 18. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 17/44 Global connections Exponential growth of devices connected through IoT!
  19. 19. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 18/44 Sensors invasion Need for low-cost, massive and controlled production of nanostructures for future sensing applications
  20. 20. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 19/44 OUTLINE 0D 1D 2D Ge QDs: not only size matters ZnO NRS: surface defect engineering ZnO NWs: flexible pH sensor NiO NF: flexible glucose sensor
  21. 21. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 20/44 Step One Seed Layer Zinc Acetate in ethanol Spin coating + Heating: 240 °C, 20 min Hot Plate Step Two Growth 90°C, 1h Aqueous bath: [Zn(NO3)2 ⋅6H2O] 25 mM [C6H12N4] 12.5-50mM L.Vayssieres et al., J.Phys. Chem. B, 105, 3350 (2001) L.E. Greene et al., Angew. Chem.I nt.. Ed. 42, 3031 (2003) Chemical bath deposition Effect of [HMTA]: pH or chelating ? 300 ZnO seeds/µm2 Hot Plate Magic formula 
  22. 22. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 21/44 ZnO NRs: HMTA effect
  23. 23. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 22/44 ZnO NRs: HMTA effect V. Strano, et al., J. Phys. Chem. C (2014) 118, 28189 HMTA effect: pH and steric hindrance
  24. 24. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 23/44 Laser irradiation of ZnO NRs Adrian M. Chitu, prof. J. Im’s group - CU G. Fiaschi, Y. Komen, Y. Shacham – TAU Laser energy flux: 100-1000 mJ/cm2 950 770 550 225 mJ/cm2
  25. 25. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 24/44 Laser irradiation of ZnO NRs 580 mJ/cm2 310 mJ/cm2 Progressive melting from the top
  26. 26. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 25/44 ZnO NRs and light Below gap light Above gap light Light emission Light scattering V. Strano, et al., Appl. Phys. Lett. (2015) E. G. Barbagiovanni, et al., Nanoscale (2015)
  27. 27. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 26/44 ZnO NRs: light emission Near band edge emission: no CBMVBM transition, FX-D (Zni donor state)! Visible band: defect states in the band gap …
  28. 28. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 27/44 Defect engineering ERDA H detection PLE Visible PL: four components (BGOR) fit, Orange line always present. PLE: excitation onset changes with annealing. ERDA: H trapped at surface, released at high T.
  29. 29. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 28/44 BGOR model E. G. Barbagiovanni, et al., Nanoscale (2015) Surface defect engineering allows modulation of visible PL in ZnO nanorods
  30. 30. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 29/44 ZnO NRs: UV sensing E. G. Barbagiovanni, et al., Appl. Phys. Lett. (2015) PL transient only for green line (surface O vacancy). PL transient = IV transient Space for optical sensing of gas
  31. 31. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 30/44 ZnO NRs - conclusion 1D ZnO NRS: surface defect engineering  Low-cost but controlled ZnO NR synthesis (HMTA role)  Laser annealing induced modification  Surface defect engineering for sensing V. Strano, et al., J. Phys. Chem. C (2014) V. Strano, et al., Appl. Phys. Lett. (2015) E. G. Barbagiovanni, et al., Nanoscale (2015) E. G. Barbagiovanni, et al., Appl. Phys. Lett. (2015)
  32. 32. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 31/44 OUTLINE 0D 1D 2D Ge QDs: not only size matters ZnO NRS: surface defect engineering ZnO NWs: flexible pH sensor NiO NF: flexible glucose sensor
  33. 33. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 32/44 ZnO nanowalls Growth upon Al film 90°C, 1h Aqueous bath: [Zn(NO3)2 ⋅6H2O] 25 mM [C6H12N4] 12.5-50mM 4 µm TOP VIEWS 200 nm 1 µm TILTED VIEW
  34. 34. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 33/44 ZnO NWs: growth Al(OH)4 - Al(OH)4 - Al(OH)4 - Substrate Al Substrate Al Substrate Al Growth Time φ s K. O. Iwu, et al., Cryst. Growth Des. (2015)
  35. 35. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 34/44 • Al/ZnO nanoporous provides a perfect conducting/selective layer for extended gate • Al/ZnO bi-layer was connected to the gate of an LTPS TFT fabricated on flexible PI pH sensor Extended Gate Thin Film Transistor (polycrystalline silicon at low temperature) ZnO NW
  36. 36. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 35/44 pH sensor Basic test for further biosensors (as Enzyme FET) involving pH variation due to Enzyme-Analite reaction - Measurements were performed @ 25 °C in dark condition and after 10 min after changing pH solution - Reference electrode Ag/AgCl - IdVg performed @ Vds=0.1 V with slow ramp rate (2 s/V) - IdVds performed @ Vg=9 V - pH-sensitivity nearly 60 mV/pH, close to ideal Nernstian response (2.3 KT=60 mV/pH)) L. Maiolo, et al., Appl. Phys. Lett. (2014)
  37. 37. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 36/44 Future glucose sensor Today  Tomorrow Less invasive Stable Low-cost Flexible Non toxic … NON-ENZYMATIC GLUCOSE SENSING Glucose in saliva 20-70 µM Glucose in tears 100-300 µM ENZYMATIC GLUCOSE SENSING Glucose in blood 3-8 mM
  38. 38. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 37/44 Non-enzymatic glucose sensing Issues with non-enzymatic sensing 1) Sensitivity (bare Pt is too low, heavy metals to enhance it: Pb, Bi, WO3 …) 2) Electroactive interference species 3) Resistance to chloride ions 4) Dissolution/Toxicity of heavy metals Advantages over enzymatic sensing 1) Able to achieve continuous glucose monitoring 2) high stability compared to traditional glucose sensors 3) ease of their fabrication 4) Pain free … K. Tian et al. / Materials Science and Engineering C 41 (2014) 100–118
  39. 39. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 38/44 Chemical bath deposition Ingredients: 1) Nickel sulfate hexahydrate 2) potassium persulfate 3) ammonia solution Mix at room temperature Substrate: FTO or ITO covered UPILEX Immersion time: 5 minutes Ni(OH)2 nanosheets 650nm
  40. 40. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 39/44 30 35 40 45 50 55 Ni (211) Ni (200) Ar90FG60 FG60 FG30 Ar90 α-Ni(OH)2 (110) α-Ni(OH)2 (111) α-Ni(OH)2 (200) NiO (111) NiO (222) XRDsignal[arb.units] Degree [°] As prep Ni nanofoam formation 100 200 300 400 500 0.0 0.5 1.0 Hconsumption[arb.un.] Temperature [°C] As prep Argon Temperature programmed reduction BET surface area ~ 25 m2/g Ni(OH)2 NiO NiO Ni nanofoam 350°C, Ar 350°C, FG
  41. 41. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 40/44 Glucose sensor CV (0 – 0.8 V vs SCE) 30 cycles, at least Y.Miao et al., Biosensors and Bioelectronics 53 (2014) 428–439 NiO NF
  42. 42. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 41/44 Glucose sensor tests 0 100 200 0.0 0.3 0.6 0.9 1.2 50µM Currentdensity[mA/cm2 ] Time [s] Ni nanofoam on FTO glass 20 µM 100µM 0.0 0.1 0.2 0.3 0.4 0.0 0.3 0.6 0.9 1.2 currentdensity[mA/cm2 ] Glucose concentration [mM] Glucose sensitivity: 2.98 mAmM-1 cm-2 V = 0.5 Volt vs. SCE Response time ∼ 1 s 0.6 0.9 1.2 0.0 0.1 0.2 0.3 0.4 0.0 0.3 0.6 0.9 1.2 2 Gl t ti [ M] Glucose sensitivity: 2.98 mAmM-1 cm-2 TearsSaliva K. O. Iwu, et al., Sensors and Actuators B (2015)
  43. 43. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 42/44 2D - conclusion 2D ZnO NWs: flexible pH sensor NiO NF: flexible glucose sensor  Controlled, inexpensive growth of large surface area material  ZnO NWs as ideal sensing nanostructure for pH  NiO NF for non-enzymatic, high sensitivity glucose sensing L. Maiolo, et al., Appl. Phys. Lett. (2014) K. O. Iwu, et al., Cryst. Growth Des. (2015) K. O. Iwu, et al., Sensors and Actuators B (2015)
  44. 44. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 43/44 Acknowledgements 0D 1D 2D Post-doc & PhD: S Cosentino, EG Barbagiovanni, R Raciti Staff: A Terrasi, M Miritello, TEM group SUPPORT: EU-NASCENT, IT-PON_PV&ENERGETIC Coll.: Brown Univ. USA, Bilkent Univ. Turkey Post-doc & PhD: EG Barbagiovanni, V Strano Staff: G Franzò, R Reitano, TEM group SUPPORT: IT-PON_PLAST_ICs Coll.: Univ. Catania, TAU Israel, CU USA Post-doc & PhD: K Iwu, V Strano Staff: G Fortunato, L Maiolo SUPPORT: IT-PON_PLAST_ICs Coll.: Univ. Catania
  45. 45. Columbia University, MSE colloquium, New York mirabella@ct.infn.it 44/44

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