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Both two-dimensional (2D) transitional metal dichalcogenides (TMDs) and III–V semiconductors have been considered as potential platforms for quantum technology. While 2D TMDs exhibit a large exciton binding energy, and their quantum properties can be tailored via heterostructure stacking, TMD technology is currently limited by the incompatibility with existing industrial processes. Conversely, III-nitrides have been widely used in light-emitting devices and power electronics but not leveraging excitonic quantum aspects. Recent demonstrations of 2D III-nitrides have introduced exciton binding energies rivaling TMDs, promising the possibility to achieve room-temperature quantum technologies also with III-nitrides. Here, we discuss recent advancements in the synthesis and characterizations of 2D III-nitrides with a focus on 2D free-standing structures and embedded ultrathin quantum wells. We overview the main obstacles in the material synthesis, vital solutions, and the exquisite optical properties of 2D III-nitrides that enable excitonic and quantum-light emitters. 

Abstract Highly-directional image artifacts such as ion mill curtaining, mechanical scratches, or image striping from beam instability degrade the interpretability of micrographs. These unwanted, aperiodic features extend the image along a primary direction and occupy a small wedge of information in Fourier space. Deleting this wedge of data replaces stripes, scratches, or curtaining, with more complex streaking and blurring artifacts—known within the tomography community as “missing wedge” artifacts. Here, we overcome this problem by recovering the missing region using total variation minimization, which leverages image sparsity-based reconstruction techniques—colloquially referred to as compressed sensing (CS)—to reliably restore images corrupted by stripe-like features. Our approach removes beam instability, ion mill curtaining, mechanical scratches, or any stripe features and remains robust at low signal-to-noise. The success of this approach is achieved by exploiting CS's inability to recover directional structures that are highly localized and missing in Fourier Space. 

Abstract Ultrawide‐bandgap semiconductors such as AlN, BN, and diamond hold tremendous promise for high‐efficiency deep‐ultraviolet optoelectronics and high‐power/frequency electronics, but their practical application has been limited by poor current conduction. Through a combined theoretical and experimental study, it is shown that a critical challenge can be addressed for AlN nanostructures by using N‐rich epitaxy. Under N‐rich conditions, the p‐type Al‐substitutional Mg‐dopant formation energy is significantly reduced by 2 eV, whereas the formation energy for N‐vacancy related compensating defects is increased by ≈3 eV, both of which are essential to achieve high hole concentrations of AlN. Detailed analysis of the current−voltage characteristics of AlN p‐i‐n diodes suggests that current conduction is dominated by hole‐carrier tunneling at room temperature, which is directly related to the activation energy of Mg dopants. At high Mg concentrations, the dispersion of Mg acceptor energy levels leads to drastically reduced activation energy for a portion of Mg dopants, evidenced by the small tunneling energy of 67 meV, which explains the efficient current conduction and the very small turn‐on voltage (≈5 V) for the diodes made of nanoscale AlN. This work shows that nanostructures can overcome the dopability challenges of ultrawide‐bandgap semiconductors and significantly increase the efficiency of devices.