Laboratory for Transport Measurements

• Karlo Veličan
• Daria Jardas Babić, PhD
• Assoc. Prof. Robert Peter, PhD
• Assoc. Prof. Ivana Jelovica Badovinac, PhD
• Assoc. Prof. Ivna Kavre Piltaver, PhD
• Assoc. Prof. Iva Šarić Janković, PhD

The Laboratory’s experimental set-up is adapted to measure the transport properties of thin semiconductor films. The types of measurements performed are:

• measurements of current – voltage (I – V) characteristics of samples, which determine the specific resistance / conductivity of the material;
• Hall voltage measurements, with which we determine the sign and concentration of charge carriers in a semiconductor;
• measurements of the time dependence of the photocurrent, with which we monitor the slow dynamics of photoexcitation in materials.

The material we primarily deal with is zinc oxide (ZnO) in the form of thin films with a thickness of 10 nm to 100 nm synthesized by the Atomic Layer Deposition (ALD) method. ZnO is a semiconductor with a wide band gap (3.2 – 3.4 eV). The property that sets it apart from other semiconducting metal oxides is the possibility of a large concentration of point defects (cavities, interstitial atoms) in the crystal structure. These defects largely determine the physical properties of ZnO. Thus, for example, the specific resistance of ZnO can take on values ​​that extend over six orders of magnitude – from 10^-3 Ωcm to 10³ Ωcm, depending on the concentration of defects. By changing the parameters of the ALD synthesis, we can obtain zinc oxide films with very different physical properties. Transport measurements provide us with useful information about the synthesized materials that serve us in further research directed towards ZnO applications in the fields of photocatalysis and photovoltaics.

1. R. Peter, A. Omerzu, I. Kavre Piltaver, R. Speranza, K. Salamon, M. Podlogar, K. Velican, M. Percic, M. Petravic, Large enhancement of visible light photocatalytic efficiency of ZnO films doped in-situ by copper during atomic layer deposition growth, Ceram. Int. 49 (22), 35229-35238.
2. D. Jardas, A. Omerzu, R. Peter, I.Kavre Piltaver, M. Petravić, Photocatalytic Activity Under UV and Solar Illumination of Thin ZnO Films Grown by Atomic Layer Deposition, Proceedings of the 3rd International Congress on Advanced Materials Sciences and Engineering, AMSE 2022.
3. A. Omerzu, R. Peter, D. Jardas, I. Turel, K. Salamon, M. Podlogar, D. Vengust, I. Jelovica Badovinac, I. Kavre Piltaver, M. Petravic, Large enhancement of photocatalytic activity in ZnO thin films grown by plasma-enhanced atomic layer deposition, Surf. Interfaces 23 (2021) 100984.
4. R. Peter, K. Salamon, A. Omerzu, J. Grenzer, I. Jelovica Badovinac, I. Saric, M. Petravic, Role of Hydrogen-Related Defects in Photocatalytic Activity of ZnO Films Grown by Atomic Layer Deposition, J. Phys. Chem. C 124 (2020), 8861
5. I. Jelovica Badovinac, R.Peter, A. Omerzu, K. Salamon, I. Šarić, A. Samaržija, M. Perčić, I. Kavre Piltaver, G. Ambrožić, M. Petravić, Grain size effect on photocatalytic activity of TiO2 thin films grown by atomic layer deposition, Thin Solid Films 709 (2020) 138215.
6. A.Omerzu, I. Saric, I. Kavre Piltaver, M. Petravic, T. Kapun, J. Zule, S. Stifter, K. Salamon, Prevention of spontaneous combustion of cellulose with a thin protective Al2O3 coating formed by atomic layer deposition, Surf. Coat. Technol. 333 (2018) 81.
7. A. Omerzu, M. Borovšak: Long-range correlated electron transport in M-DNA, Chemical Physics 478 (2016) 45.
8. M. Strojnik, A. Omerzu, A. Majkić, P. M. Mihailovic, J. Lukan, G. Bavdek, G. Bratina, D. Cvetko, P. Topolovsek, D. Mihailovic: Valence band and energy gap of MoSI molecular wires, Langmuir 27 (2011) 4296.
9. A. Omerzu, B. Anzelak, I. Turel, J. Strancar, A. Potocnik, D. Arcon, I. Arcon, D. Mihailović, H. Matsui: Strong correlations in highly electron-doped Zn(II)-DNA complexes, Phys. Rev. Lett. 104 (2010),156804.
10. A. Omerzu, M. Licer, T. Mertelj, V. V. Kabanov, D. Mihailovic: Hole interactions with molecular vibrations on DNA, Phys. Rev. Lett 93 (2004) 218101.
11. T. Vuletic, D. Herman, N. Biskup, M. Pinteric, A. Omerzu, S. Tomic, M. Nagasawa: Single-particle and spin-density wave charge dynamics in (TMTSF)(2)PF6 and (TMTSF)(2)AsF6: A comparative overview, J. Phys. IV 9 (1999) 275.
12. A. Omerzu, D. Mihailovic, N. Biskup, O. Milat, S. Tomic: Electrical transport measurements on TDAE-C-60 single crystals, Synthetic Met. 85 (1997) 1723.
13. A. Omerzu, D. Mihailovic, S. Tomic, O. Milat, N. Biskup: Electrical conductivity in dynamically orientationally disordered systems: ac and dc measurements in ferromagnetic single crystals of TDAE-C-60, Phys. Rev. Lett. 77 (1996) 2045.

System for measuring electrical conductivity and the Hall effect

• Current-voltage source Keithley 2401
• Electromagnet: 0 < B < 0.6 T

Programmable furnace Carbolite Gero

UV-Vis spectrophotometer EVOLUTION 201

• measurement of optical absorption in the spectral range from 200 nm to 1100 nm