Earth-abundant ZnSn_xGe_(1−x)N_2 alloys as potential photovoltaic absorber materials

Large-scale energy demands will require low-cost, earth-abundant materials for high efficiency solar energy conversion. Here we present ZnSn_xGe_(1−x)N_2 as a tunable band gap photovoltaic absorber layer with a predicted range of 1.4 eV to 2.9 eV. Thin films of ZnSn_xGe_(1−x)N_2 are synthesized by reactive RF co-sputtering with a wide range of compositions. X-ray diffraction shows a linear shift in lattice parameter with changing composition, indicating no phase separation. These results suggest that ZnSn_xGe_(1−x)N_2 can potentially be tuned to span a large portion of the solar spectrum and could therefore be a viable earth-abundant photovoltaic material

Mg doping and its effect on the semipolar GaN(112¯2) growth kinetics

International audienceWe report the effect of Mg doping on the growth kinetics of semipolar GaN(112¯2) synthesized by plasma-assisted molecular-beam epitaxy. Mg tends to segregate on the surface, inhibiting the formation of the self-regulated Ga film which is used as a surfactant for the growth of undoped and Si-doped GaN(112¯2). We observe an enhancement of Mg incorporation in GaN(112¯2) compared to GaN(0001). Typical structural defects or polarity inversion domains found in Mg-doped GaN(0001) were not observed for the semipolar films investigated in the present study

Interband and intersubband optical characterization of semipolar (112¯2)-oriented GaN/AlN multiple-quantum-well structures

International audienceWe report on semipolar GaN/AlN multiple-quantum-well structures grown on m-plane sapphire by plasma-assisted molecular-beam epitaxy. Optical investigation confirms a significant reduction in the quantum-confined Stark effect, in agreement with theoretical calculations, which predict an internal electric field between 0.6 and −0.55 MV/cm in the quantum wells, depending on the strain state. With respect to polar materials, the reduction in the internal electric field results in a substantial redshift of the intersubband energy

Polar and Semipolar III-Nitrides for long wavelength intersubband devices

International audienceExtending the intersubband transitions in III-nitride nanostructures from near-infrared to longer wavelengths might have significant consequences for critical applications like imaging, remote sensing and mine detection. In this work, we analyze the potential of polar and semipolar AlGaN/GaN technologies for this relevant spectral range

Enhancement of Auger recombination induced by carrier localization in InGaN/GaN quantum wells

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