María Sánchez

2023 Conference

Surface Photovoltage Spectroscopy in characterization of materials and devices
M. Sánchez
Faculty of Physics. University of Havana. San Lázaro and L, Vedado, 10400.
La Habana, Cuba
maruchy@fisica.uh.cu

 

Surface Photovoltage spectroscopy (SPS) is a widely used technique to study the electronic transitions and optical properties of semiconductor materials and nanostructures. This technique relies on measuring changes in the surface voltage as a function of the incident wavelength.


In this talk, the fundamentals and experimental details of SPS are presented. Results obtained in characterization of: p-Cu2O/n-ZnO nanojunctions, InxGa1-xN self-assembled nanostructures1 and MoO3 thin films2 are presented. Experiments on the temperature dependence of the surface photovoltage (SPV) in InxGa1-xAs QWs have been performed between 20 and 275 K, demonstrating that quantum well transitions and barriers can be clearly identified even at room temperature. A specially designed sample holder was used for the SPV measurements3. Finally, we report on an original application of SPV for characterization of fully metallized AlxGa1-xAs laser4 diodes and c- silicon solar cells demonstrating the effectiveness of this technique as a simple, contactless and non-destructive tool in the characterization not only of materials but also in semiconductor devices. Kelvin Probe Force Microscopy (KPFM) was used for direct measurement of surface potential maps.

SPV spectrum of a MoO3 sample and derivative of the SPV signal. Features corresponding to near band gap transition and defect states are clearly identified.
SPV spectrum of an AlGaAs laser diode. The signals coming from GaAs substrate, AlGaAs active region and barriers are well noticed

References

  1. Indium incorporation at InxGa1-xN relaxed self-assembled nanostructures on Si substrates, Mater. Sci. Semicond. Process, Vol. 150, 106946, 2022.

  1. Optical and electrical properties of MoO2 and MoO3 thin films prepared from the chemically driven isothermal close space vapor transport technique, J. Phys.: Condens. Matter, Vol. 31, 295703, 2019.

  1. Automated system for surface photovoltage spectroscopy, Rev. Sci. Instrum., Vol. 92, 013104, 2021.

  2. Surface photovoltage spectroscopy characterization of AlGaAs/GaAs laser structures, Journal of Physics: Conf. Series Vol. 792, 012021, 2017.