We exfoliated bulk GaGeTe crystals down to ultrathin flakes using the scotch tape method and fabricated field effect transistors (FETs). The GaGeTe FETs display a p-type behavior with drain current modulation on the order of 103, hole mobility of 0.45 cm2 V−1 s−1, and photoresponsivity of 3.6 A W−1 at room temperature. These findings suggest that the layered GaGeTe is a promising 2D semiconductor for fabricating devices, such as transistors and photodetectors.

We report the discovery of superconductivity at ∼9 K in Fe 1.05 Te single crystals that have been exposed to air for more than six months. The superconductivity is induced due to the oxygen incorporation and only exists in the surface layer of the samples. Our high-resolution transmission electron microscopy experiments and density functional theory calculations show the oxygen prefers to locate at the interstitial site in the Fe-Te layer. X-ray photoelectron spectra characterize an enhancement of the itinerant character of Fe 3d electrons, which may reduce the local moment and hence suppress the long-range antiferromagnetism associated with superexchange interactions. This work suggests the bicollinear antiferromagnetism in Fe 1+y Te can be suppressed by oxygen incorporation to induce superconductivity and thus could be considered as the parent phase of the superconductivity.

Two-dimensional conjugated polymers (2DCPs), composed of multiple strands of linear conjugated polymers with extended in-plane π-conjugation, are emerging crystalline semiconducting polymers for organic (opto)electronics. They are represented by two-dimensional π-conjugated covalent organic frameworks, which typically suffer from poor π-conjugation and thus low charge carrier mobilities. Here we overcome this limitation by demonstrating two semiconducting phthalocyanine-based poly(benzimidazobenzophenanthroline)-ladder-type 2DCPs (2DCP-MPc, with M = Cu or Ni), which are constructed from octaaminophthalocyaninato metal(ii) and naphthalenetetracarboxylic dianhydride by polycondensation under solvothermal conditions. The 2DCP-MPcs exhibit optical bandgaps of ~1.3 eV with highly delocalized π-electrons. Density functional theory calculations unveil strongly dispersive energy bands with small electron–hole reduced effective masses of ~0.15m0 for the layer-stacked 2DCP-MPcs. Terahertz spectroscopy reveals the band transport of Drude-type free carriers in 2DCP-MPcs with exceptionally high sum mobility of electrons and holes of ~970 cm2 V−1 s−1 at room temperature, surpassing that of the reported linear conjugated polymers and 2DCPs. This work highlights the critical role of effective conjugation in enhancing the charge transport properties of 2DCPs and the great potential of high-mobility 2DCPs for future (opto)electronics.