Photoinduced bleaching in Ga-Ge-S(Se) vitreous films

Vitreous films in the Ga-Ge-S(Se) system are prepared through pulsed laser deposition and investigated. An analysis of the data of Raman and energy-dispersive X-ray spectroscopy demonstrates that the composition and structure of the films are similar to those of the monolithic glass. Exposure of the films to radiation with an energy higher than the band gap leads to bleaching of sulfur-based films due to the local oxidation of the films as judged from the data of infrared, Raman, and energy-dispersive X-ray spectroscopy. The replacement of sulfur by selenium in the composition of the films results in the opposite effect: irradiation of the films brings about the photoinduced darkening. Examination of the samples with the use of a scanning electron microscope does not reveal a substantial change in the morphology of the films under irradiation. The observed effect is used to write a copy of the diffraction grating with a resolution of 1200 grooves/mm.     

Photoelectric properties of structures based on TlInS2 single crystals

The photovoltaic effect in heterocontacts of various types, viz., In/TlInS₂, InSe/TlInS₂, and GaSe/TlInS₂, is investigated. The relative photoconversion quantum efficiency of these structures is studied as a function of the energy of the incident photons and the polarization plane of linearly polarized light. It follows from photosensitivity measurements that the photosensitive structures obtained can be employed as broad-band and selective photosensors of optical radiation. Fiz. Tekh. Poluprovodn. 32, 78–81 (January 1998)     

Organic semiconductor-based photonic crystals for solar cell arrays: band gap and optical properties

Photonic crystals (PCs) hold great potential for designing new optical devices because of the possibility of the manipulation of light with PCs. There has been an increase in research on tuning the optical properties of PCs to design devices. We design organic semiconductor-based PC structures and calculate optical properties using the plane wave expansion method and finite-difference time-domain method in an air background for a hexagonal lattice. We showed the possibility of the solar cell arrays for a 2D PC cavity on an organic semiconductor base infiltrated with a nematic liquid crystal. E7 type has been used as a nematic liquid crystal and 4,4′-Bis[4-(diphenylamino) styryl]biphenyl as an organic semiconductor material.     

Fabrication of ZnO-based metal–insulator–semiconductor diodes by ion implantation

A ZnO-based metal–insulator–semiconductor junction has been fabricated using an isolation layer fabricated by N⁺ ion implantation. I–V dependences show a good rectifying diode-like behavior with a low leakage current of 10⁻⁶ A and a threshold voltage of about 3 V. Ultraviolet light emission under forward bias exhibits a wavelength maximum of 388 nm and a full width at half maximum of 128 meV at room temperature.     

Transport properties of TlIn1−x Ga x Se2 (0 ≤ x ≤ 0.3) crystals

Single crystals of TlIn_1?x Ga _x Se₂ solid solutions have been grown by the Bridgman-Stockbarger method. As shown by x-ray diffraction, the solid solutions crystallize in tetragonal symmetry, and their lattice parameters decrease with decreasing average atomic weight. The electrical conductivity and Hall coefficient of the solid solutions have been measured as functions of temperature, and their principal semiconductor parameters have been determined. Pseudopotential band-structure calculations have been used to analyze the origins of the valence and conduction bands in the parent compound TlInSe₂. The results indicate that the increase in the band gap of the TlIn_1?x Ga _x Se₂ solid solutions upon partial gallium substitution for indium in TlInSe₂ is due to the shift of its valence band to lower energies.     

Fundamental absorption edge in TlnS2xSe2(1-x) solid solutions

The fundamental absorption edge in TlInS_2xSe_2(1-x) Solid solutions in the energy region hν = 1.8-3.0 eV at T=100-300 K including phase transition region has been investigated in present paper. Temperature behaviour of energy gap near the phase transition region has been analyzed.