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Based on the photovoltaic properties and tandem solar cells theory, Gallium Indium Arsenide/Germanium Stannide (GaInAs/GeSn)-based double-junction (DJ) solar cells have been numerically simulated for the first time. In this study, we explore the band gap combination under lattice matching and obtain the content of In/Sn at optimal efficiency, which is expressed as Ga _0.84 In _0.16 As/Ge _0.93 Sn _0.07 DJ solar cell (1.20/0.58 eV). Afterward, it is optimized in terms of variation in the doping contents and active layer thickness. To take full advantage of the electron mobility of the material, the optimal ‘inverted doping profile’ concentration N _a(d) is 1.5(5)/5(20) × 10 ^18 cm ^−3 . In addition, the reasonable p ( n ) layer thickness could be comprised of 0.2–0.8(0.2–1)/0.5–3(1–4) μ m of the DJ solar cells with less material consumption. When the p ( n ) layer thickness is 0.30(0.25)/0.9(1.35) μ m, the tandem device can achieve an optimal efficiency of 31.00% with 28.98 mA cm ^−2 ( J _sc ), 1.25 V ( V _oc ) and 85% ( FF ). This study highlights that GeSn materials have the potential to combine with III–V materials to form low-cost and high-efficiency tandem devices.

A prototype In _0.53 Ga _0.47 As p ^+ -i-n ^+ x-ray photodiode, fabricated from material grown by metalorganic vapour phase epitaxy, was investigated as a novel detector of x-rays. The detector was connected to a custom low-noise charge sensitive preamplifier and standard readout electronics to produce an x-ray spectrometer. The detector and preamplifier were operated at a temperature of 233 K (−40 °C). An energy resolution of 1.18 keV ± 0.06 keV Full Width at Half Maximum at 5.9 keV was achieved. This is the first time InGaAs (GaInAs) has been shown to be capable of spectroscopic photon counting x-ray detection.

Synesius, bishop of Ptolemais, played an important role in the intellectual life of the Roman Empire on the turn of IV–V centuries. The article is devoted to the life and activity of Synesius in the context of his literary works that reflected the main milestones of the transition period. This article also focuses on Synesius` political and social views, which had a great impact on formation of anti-barbarian moods in the Late Ronan society.