Mo thin films have been deposited using a DC magnetron sputtering system with an S-gun configuration electrode and characterized electrically and morphologically. The influence of the sputtering gas pressure and glow discharge (GD) power, on the electrical resistivity of Mo thin films and on the contact resistivity of Mo to Cu(In,Ga)Se2 (CIGS) films was determined through an exhaustive parameter study. This study also allowed us to find the conditions to deposit Mo films with suitable properties for its use as back contact of solar cells based on CIGS. Resistivities smaller than 1x10-4 omega.cm and contact resistivities smaller than 0.3 omegacm² were found. Mo films with these characteristics are suitable for back contacts in solar cells based on CIGS. It was also found that the Mo thin films, deposited by DC magnetron sputtering on CIGS thin films, act effectively as ohmic contacts. The main contribution of this work was to obtain Mo thin films with adequate properties to be used as back contact for CIGS based solar cells using a DC sputtering system with S-gun configuration electrode, which allows growing the film with better surface quality and at a higher deposition rate than those deposited using the conventional planar RF sputtering system.

Thin films of ${\text{Cu}}_3{\text{BiS}}_3$ were prepared by coevaporation. Hall-effect, Seebeck-effect, and surface photovoltage measurements show that ${\text{Cu}}_3{\text{BiS}}_3$ is a p-type semiconductor with Hall-mobility, free carrier concentration, and thermo-electric power of $4{\text{cm}}^2/\text{V}\text{s}$ , $2\times {10}^{16}{\text{cm}}^{-3}$ , and 0.73 mV/K, respectively. The work function was determined by Kelvin probe force microscopy to be $\left(4.37\pm 0.04\right)\text{eV}$ before and $\left(4.57\pm 0.01\right)\text{eV}$ after deposition of a thin ${\text{In}}_2{\text{S}}_3$ layer. Transient surface photovoltage measurements at variable excitation wavelength showed the importance of defect states below the band gap for charge separation and the opportunity for surface defect passivation by a very thin ${\text{In}}_2{\text{S}}_3$ layer. The band bending at the ${\text{Cu}}_3{\text{BiS}}_3/{\text{In}}_2{\text{S}}_3$ interface was obtained. The role of grain boundaries for charge transport and charge separation is discussed.

We have carried out first-principles spin polarized calculations to obtain comprehensive information regarding the structural, magnetic, and electronic properties of the Mn-doped GaSb compound with dopant concentrations: x = 0.062, 0.083, 0.125, 0.25, and 0.50. The plane-wave pseudopotential method was used in order to calculate total energies and electronic structures. It was found that the Mn_Ga substitution is the most stable configuration with a formation energy of ∼1.60 eV/Mn-atom. The calculated density of states shows that the half-metallic ferromagnetism is energetically stable for all dopant concentrations with a total magnetization of about 4.0 μ_B/Mn-atom. The results indicate that the magnetic ground state originates from the strong hybridization between Mn-d and Sb-p states, which agree with previous studies on Mn-doped wide gap semiconductors. This study gives new clues to the fabrication of diluted magnetic semiconductors.