Van der Waals (vdW) semiconductors are attractive for highly scaled devices and heterogeneous integration since they can be isolated into self-passivated, two-dimensional (2D) layers that enable superior electrostatic control. These attributes have led to numerous demonstrations of field-effect devices ranging from transistors to triodes. By exploiting the controlled, substitutional doping schemes in covalently-bonded, three-dimensional (3D) semiconductors and the passivated surfaces of 2D semiconductors, one can construct devices that can exceed performance metrics of "all-2D" vdW heterojunctions. Here, we demonstrate, 2D/3D semiconductor heterojunctions using MoS 2 as the prototypical 2D semiconductor laid upon Si and GaN as the 3D semiconductor layers. By tuning the Fermi levels in MoS 2 , we demonstrate devices that concurrently exhibit over seven orders of magnitude modulation in rectification ratios and conductance. Our results further suggest that the interface quality does not necessarily affect Fermi-level tuning at the junction opening up possibilities for novel 2D/3D heterojunction device architectures.

An efficient and highly regioselective protocol was developed for the preparation of 5-hydroxy-2-isoxazolines, which have been proved to be versatile synthons for isoxazles, beta-hydroxy oximes, and gamma-amino alcohols. Beta-lactams, commonly embedded in the skeletons of bioactive natural products, were also synthesized in two steps from beta-hydroxy oximes, providing a new strategy for the synthesis of this kind of compounds.

Two-dimensional (2D) infrared photodetectors always suffer from low quantum efficiency (QE) because of the limited atomically thin absorption. Here, we reported 2D black phosphorus (BP)/Bi 2 O 2 Se van der Waals (vdW) photodetectors with momentum-matching and band-alignment heterostructures to achieve high QE. The QE was largely improved by optimizing the generation, suppressing the recombination, and improving the collection of photocarriers. Note that momentum-matching BP/Bi 2 O 2 Se heterostructures in k -space lead to the highly efficient generation and transition of photocarriers. The recombination process can be largely suppressed by lattice mismatching–immune vdW interfaces. Furthermore, type II BP/Bi 2 O 2 Se vdW heterostructures could also assist fast transport and collection of photocarriers. By constructing momentum-matching and band-alignment heterostructures, a record-high QE of 84% at 1.3 micrometers and 76.5% at 2 micrometers have been achieved in BP/Bi 2 O 2 Se vdW photodetectors.

A series of 3-substituted and 3,5-disubstituted isoxazoles have been efficiently synthesized in moderate to excellent yields by the reaction of N-hydroxyl-4-toluenesulfonamide with alpha,beta-unsaturated aldehydes/ketones. This novel strategy is associated with readily available starting materials, mild conditions, high regioselectivity, and wide scope.