Hybrid silicon solar cells have been fabricated by the spin coating of conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as a p-type contact on textured n-type crystalline silicon wafers. The effect of adding co-solvents, ethylene glycol (EG) and dimethyl sulphoxide (DMSO), to PEDOT:PSS improves its conductivity which translates to the improved performance of solar cells. Transfer length measurements were conducted to realize optimal contact with minimal losses between the front metal contact (silver) and PEDOT:PSS. From the conductivity and device results, a 7% EG with 0.25 wt% Triton (surfactant) blend of PEDOT:PSS is found to be optimal for these cells. This current approach with a few changes in the device architecture will pave way for the further improvement of PEDOT:PSS based hybrid silicon solar cells.

We report on the molecular beam epitaxy growth and characterization of TbAs films. In situ reflection high energy electron diffraction and ex situ high resolution X-ray diffraction, reciprocal space mapping, and both scanning and transmission electron microscopy are used to confirm the complete film growth and study the films' morphology. Spectrophotometry measurements provide the energy of optical transitions, revealing a red shift in optical band gap with increasing thickness. The Hall effect measurements show temperature insensitive carrier concentrations, resistivities, and mobilities. The carrier concentration decreases and resistivity increases with increasing film thickness; mobility appears thickness independent. The films' reflectivity, obtained via Fourier transform infrared spectroscopy, shows a possible Drude edge that differs from the trend of other lanthanide monopnictides. These measurements show that TbAs is a degenerately doped semiconductor with a combination of electronic and optical properties that is dissimilar to other lanthanide monopnictides.

We explore the growth and characterization of ErAs:GaBiAs as a candidate material for terahertz generation and detection via photoconductive switches. Spectrophotometry shows that the incorporation of small amounts of bismuth causes a reduction in the band gap, making these materials compatible with fiber-coupled lasers. ErAs pins the Fermi level within the band gap, causing high dark resistance while maintaining high mobility, shown by Hall effect measurements. Finally, transient absorption (optical pump, optical probe) measurements show that the ErAs provides a carrier recombination pathway, causing short carrier lifetimes. These material properties make ErAs:GaBiAs an interesting choice for fiber-coupled photoconductive switches.

The thermal stability of ErAs nanoparticles and bulk-like powders, synthesized by pulsed laser ablation and direct reaction, respectively, is investigated up to 700 °C in N2. Thermogravimetric analysis and XRD are used to monitor the decomposition temperatures and crystalline compositions of the synthesized powders, respectively. Degradation of unagglomerated nanoparticle powders is observed at 350 °C accompanied by the crystallization of amorphous Er2O3. Mass balance analysis suggests that the mass loss occurs as a result of arsenic volatilization rather than congruent sublimation of ErAs. Conversely, micron-sized agglomerated particles grown by direct reaction show little evidence for degradation under similar thermal processing conditions. This significant decrease in ErAs stability compared to agglomerated powders suggests a size dependence on the degradation characteristics of ErAs.

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