The optical generation of an out-of-equilibrium spin population is a keystone process for quantum technologies and spintronics alike. Although this is an established technique for studying direct band-gap semiconductors, it has been proven limited in materials that possess weak oscillator strengths for the optical transitions. We address the problem by presenting an all-optical analog of the spin-pumping method. By applying this concept to a Ge-on-Si heterostructure, we observe luminescence from Si with a polarization degree as high as 9%. The progressive etching of the absorbing layer, assisted by magneto-optic experiments, allows us to ascertain that the polarized emission is determined by effective spin injection aided by the carrier lifetime shortening due to extended defects. These findings can facilitate the use of highly promising spin-dependent phenomena of Si, whose optical exploitation has been hampered by fundamental limitations due to its peculiar electronic structure.

Tellurium (Te) is a p-type semiconductor with a narrow bandgap, promising for infrared optoelectronics. This work presents a solution-based synthesis of novel single-crystal Te nanocubes and polycrystalline films. Te is dissolved in ethylenediamine-ethanethiol, mixed with ethanolamine, and spin-coated to form nanocrystals and films. We achieved monodispersed single-crystal Te nanocubes ∼500–900 nm in size, confirmed by electron microscopy and diffraction. The crystal morphology can be tuned by the annealing temperature and air exposure time. We show patterning of Te nanocubes by exploiting the deposition dependence on the substrate's wetting properties. We also demonstrate ∼500 nm thick polycrystalline Te films processed in air at 150°C. The Te films exhibit p-type behavior, an electrical resistivity of 0.115 Ω·cm, and photoconductance at wavelengths up to 2100 nm without optical cavities or complex gain mechanisms. The films exhibit responsivities of 0.93 A W⁻¹ at 1720 nm and 137 mA W⁻¹ at 2100 nm under intensities of 0.98 and 6.4 mW/cm², respectively. The large dark current remains a limitation for the current photoconductor configuration, but device engineering can improve speed and ON/OFF ratio. Overall, this low-temperature method provides an alternative, cost-effective pathway for Te-based infrared optoelectronics beyond the operating ranges of Si, Ge, and conventional InGaAs.