Device-quality hydrogenated amorphous silicon containing as little as 1/10 the bonded H observed in device-quality glow discharge films have been deposited by thermal decomposition of silane on a heated filament. These low H content films show an Urbach edge width of 50 mV and a spin density of ∼1/100 as large as that of glow discharge films containing comparable amounts of H. High substrate temperatures, deposition in a high flux of atomic H, and lack of energetic particle bombardment are suggested as reasons for this behavior.

Solar cells based on kesterite absorbers consistently show lower voltages than those based on chalcopyrites with the same bandgap. We use three different experimental methods and associated data analysis to determine minority-carrier lifetime in a 9.4%-efficient Cu 2 ZnSnSe 4 device. The methods are cross-sectional electron-beam induced current, quantum efficiency, and time-resolved photoluminescence. These methods independently indicate minority-carrier lifetimes of a few nanoseconds. A comparison of current-voltage measurements and device modeling suggests that these short minority-carrier lifetimes cause a significant limitation on the voltage produced by the device. The comparison also implies that low minority-carrier lifetime alone does not account for all voltage loss in these devices. V C 2013 AIP Publishing LLC. [http://dx.

We describe the design and performance of a three-terminal tandem solar cell for low-concentration terrestrial applications. Designed for operation under a GaAs filter, the tandem demonstrates cumulative conversion efficiencies of 10.2 and 11.9% at 1 sun and 45 suns, respectively, under the concentrated direct spectrum. The middle terminal is shared between the two subcells and allows them to be operated independently at their respective maximum power points.

We discuss lattice-mismatched (LMM) approaches utilizing compositionally step-graded layers and buffer layers that yield Ill-V photovoltaic devices with performance parameters equaling those of similar latticematched (LM) devices. Our progress in developing highperformance. LMM, InP-based GalnAshAsP materials and devices for thermophotovoltaic (TPV) energy conversion is highlighted. A novel, monolithic. multibandgap, tandem device for solar PV (SPV) conversion involving LMM materials .is also presented along with promising preliminary performance results.

We measured the recombination lifetime of degenerate n-InxGa1−xAs for three different compositions that correspond to x=0.53, 0.66, and 0.78 (band gaps of 0.74, 0.60, and 0.50 eV, respectively) over the doping range of 3×1018–5×1019 carriers/cm3. The Auger recombination rate increases slowly with decreasing band gap, and it matches the behavior predicted for phonon-assisted recombination.