Near band-edge optical properties of cubic GaN with and without carbon doping
We report the results of studying the optical properties of cubic GaN thin films with photoluminescence and photoluminescence excitation spectroscopies. The films are deposited by plasma-assisted molecular beam epitaxy on GaAs (001) substrates, with and without intentional doping with carbon atoms (p-type doping). The evolution of the optical spectra of the C-doped samples is consistent with a picture in which carbon enters into N-vacancies at low concentrations, producing a marked improvement in the crystalline properties of the material. At higher concentrations it begins to form complexes, possibly due to interstitial occupation. The temperature dependence on the absorption edge of the doped material is also measured and is analyzed with standard theoretical models.
Carbon-doped Sb2S3 thin films: Structural, optical and electrical properties
Abstract We report the modification of electrical properties of chemical-bath-deposited antimony sulphide (Sb 2 S 3 ) thin films by thermal diffusion of carbon. Sb 2 S 3 thin films were obtained from a chemical bath containing SbCl 3 and Na 2 S 2 O 3 salts at room temperature (27 °C) on glass substrates. A carbon thin film was deposited on Sb 2 S 3 film by arc vacuum evaporation and the Sb 2 S 3 –C layer was subjected to heating at 300 °C in nitrogen atmosphere or in low vacuum for 30 min. The value of resistivity of Sb 2 S 3 thin films was substantially reduced from 10 8  Ω cm for undoped condition to 10 2  Ω cm for doped thin films. The doped films, Sb 2 S 3 :C, retained the orthogonal stibnite structure and the optical band gap energy in comparison with that of undoped Sb 2 S 3 thin films. By varying the carbon content (wt%) the electrical resistivity of Sb 2 S 3 can be controlled in order to make it suitable for various opto-electronic applications.
Photoreflectance characterization of vanadium-doped GaAs layers grown by metalorganic vapor phase epitaxy
Abstract We characterized the vanadium-doped (GaAs:V) layers grown on GaAs substrate by metalorganic vapor phase epitaxy. The conductivity of the samples is checked by the Hall effect measurements, and it is n type with electrons concentration ranging from 2×10 13 to 2×10 17  cm −3 . We used the photoreflectance technique (PR) to study the effect of vanadium doping on the optical properties of GaAs. Our experimental results show that the built-in electric field F and the broadening parameter Γ 0 increase with V-doping concentration. Furthermore, the temperature dependence of the built-in electric field and the broadening parameter of GaAs:V samples have been investigated by PR. It has been observed that these parameters increase with increasing temperature. The decrease of the built-in electric field with decreasing temperature is due to the photovoltage effect.We characterized the vanadium-doped GaAs (GaAs:V) layers grown on GaAs substrate by metalorganic vapor phase epitaxy.