Semiconducting Glasses

Amorphous and non-crystalline materials represent a kind of inorganic polymers with interesting properties like photo-induced phenomena, luminescence, specific optical properties namely high transmission in the infrared region and high values of non-linear refractive index.
   The main focus of the group is on research of preparation, structural characterization and physical properties of non-crystalline solids based on sulphides and selenides of the elements like As, Sb, Bi, Pb, Ge, Ga, Te.  Studied are “pure” and by rare earth elements modified materials. An accent is given to an understanding of the connection along the line: chemical composition - structural arrangement – property – targeted modification of some selected physical properties.
   The methods of preparation include glasses preparation by controlled cooling, thin films preparation by thermal evaporation and by laser ablation in cooperation with Research Centre LC523 and Department of General and Inorganic Chemistry (DGICh). In the last years, together with DGICh, we started with preparation and study of some physical properties of oxide glasses based on heavy metal oxides.
Of interest are mainly:
(i) luminescence in the region of telecommunication window at around 1.3 and 1.5 μm,
(ii) interaction of the light with amorphous chalcogenides leading to  structural changes inclusive nano-phase changes,
(iii) relaxation in the glass-transition region and crystallization from amorphous/glassy state and
(iv) glasses based on heavy metal oxides prospective for non-linear optics.
 
   The work is divided into the following parts:
  • - Optimizing of amorphous chalcogenides matrix to improve dissolution of rare earth elements and increase luminescence efficiency.
  • - Photo-induced changes of amorphous chalcogenide films namely photo-darkening, photo-expansion and photo-refraction.
  • - Power compensated DSC in the region of the glass-transition temperature, DTA in the region of crystallization combined with the optical microscopy. 
  • - Optical band gap and structural make-up of new heavy metal oxide glasses with high linear refractive index and with promising non-linear refractive index.
 
 AFM image of hexagonal crystalline nuclei induced by UV photons on Ge39Ga2S59 film