Holon Physics Seminar

Thin Films and Related Structures of Oxide and Layered III−VI Group Semiconductors: Opto-Electronic and Energy Applications
Prof. Liviu Leontie, University of Iasi, Romania

May 18, 2017 | 11:00 | Room 424/8

The first part of this talk focuses on the study of structural, optical, photosensitivity and photoelectric properties of metal oxides (with a special focus on bismuth oxide, a material with multiple actual and potential technological applications) in thin films, prepared under different conditions.
The paramount influence of deposition parameters on the phase composition, optical response and photosensitive behavior is emphasized. The second part of the talk is focused on the investigation of layered III-VI materials and related lamellar composites and structures with a huge untapped application potential.
Relevant results will be introduced in terms of optical, photoluminescence and photosensitivity properties, in relation with the transport and generation-recombination processes of minority charge carriers.
Investigations of the optical properties of undoped and Cu-doped GaSe reveal peculiar particularities of excitonic absorption in their optical spectra, alongwith strong optical anisotropy (ratio of the absorption coefficients of GaSe is 15).
It was found that the presence of native oxide (Ga2O3) layer at the surface of GaSe lamellas might play an important role in future photoreceiver, solar cell and gas sensing structures. Photoluminescence (PL) data revealed the nature of recombination levels in pristine and Cu-doped GaS single crystals.
Additional results will be discussed with respect to transport and generation-recombination processes in GaSe(Cu) lamellas, where trap levels are related with the Cu impurity canters.
The specific structural features of layered III-VI semiconductors enable the intercalation of divers atomic (molecular) ions between chalcogen planes, thus leading to formation of novel lamellar nanocomposites/nanostructures, again showing promise for applications.
Optical, PL and photosensitivity properties of some lamellar nanocomposites (GaTe−CdTe, GaSe−CdSe, GaS−CdS, InSe−CdSe) will be discussed in the last part of the talk. The talk is concluded with an overview of the past and current achievements, and future insights in the field of layered III-VI semiconductors and novel III-VI/metal oxide structures.