Although the irreplaceable position of silicon (Si) semiconductor materials in the field of information has become a consensus, new materials continue to be sought to expand the application range of semiconductor devices. Among them, research on wide bandgap semiconductors has already achieved preliminary success, and the relevant achievements have been applied in the fields of energy conversion, display, and storage. However, similar to the history of Si, the immature material grown and device manufacturing processes at the current stage seriously hinder the popularization of wide bandgap semiconductor-based applications, and one of the crucial issues behind this is the defect problem. Here, we take amorphous indium gallium zinc oxide (a-IGZO) and 4H silicon carbide (4H-SiC) as two representatives to discuss physical/mechanical properties, electrical performance, and stability from the perspective of defects. Relevant experimental and theoretical works on defect formation, evolution, and annihilation are summarized, and the impacts on carrier transport behaviors are highlighted. State-of-the-art applications using the two materials are also briefly reviewed. This review aims to assist researchers in elucidating the complex impacts of defects on electrical behaviors of wide bandgap semiconductors, enabling them to make judgments on potential defect issues that may arise in their own processes. It aims to contribute to the effort of using various post-treatment methods to control defect behaviors and achieve the desired material and device performance.

Artificially stacked van der Waals heterostructures (vdWH) of two-dimensional (2D) atomic layers have attracted considerable attention due to substantial interactions between different layers. In particular, the strongly bound interlayer exciton (IX) within vdWH offers a platform for exploring fundamental physics as well as innovative device applications. However, to date, it remains a critical challenge to modulate the IX emission energy, limiting the achievement of high-performance spin-valleytronics and excitonic devices. Here, we report a simple strain engineering approach to efficiently modulate the MoS₂/WSe₂ IX via uniaxial strain. By encapsulating the vdWH within a flexible substrate, the applied mechanical strain could be effectively transferred to the lattice of vdWH during the mechanical bending process, leading to an unprecedent IX modulation range of 144 meV with a linear fitted gauge factor of 121.8 meV per 1% strain. Furthermore, we found that the gauge factor of IX in vdWH is larger than that of individual MoS₂ and WSe₂ intralayer excitons, further confirming that the observed IX originates from the momentum-indirect exciton between the K point of the MoS₂ conduction band and the Γ point of the WSe₂ valence band. Our study not only achieves a high vdWH IX modulation value using efficient strain engineering but also provides a route to investigate the evolution of band energy for various two-dimensional (2D) materials as well as their vertical vdWH.

Barrier detectors such as nBn and pBp architectures (formed by a n- or p-type contact layer, a barrier layer and a n- or p-type absorber) aim to block one carrier type while allowing the other to pass, but require complex hetero-integration and precise band engineering. Here, we propose an ultra-thin polar barrier strategy using a 0.75 nm water-intercalated WSe₂/H₂O/PdSe₂ heterostructure. The confined water layer forms a clean, well-ordered interface and further generates a precisely oriented polarization field that depletes electrons in WSe₂, significantly suppressing dark current to sub-pA levels across all biases, while enabling efficient tunneling of photogenerated holes. The device shows broadband photoresponse from the ultraviolet to mid-wave infrared (MWIR), with a room-temperature average detectivity exceeding 10¹⁰ cm Hz¹^/² W⁻¹ in the MWIR. It also features ultrafast response (~3 μs), polarization light sensitivity, and two-year stability. Our work establishes a platform for high-performance infrared photodetection via van der Waals gap engineering.

Due to the unique outermost orbitals of Sn, hole carriers in tin monoxide (SnO) possess small effective mass and high mobility among oxide semiconductors, making it a promising p-channel material for thin film field-effect transistors (TFTs). However, the Sn vacancy induced field-effect mobility deterioration and threshold voltage (V _th) shift in experiments greatly limit its application in complementary metal-oxide-semiconductor (CMOS) transistors. In this study, the internal mechanism of vacancy defect compensation by aluminum (Al) doping in SnO _x film is studied combining experiments with the density functional theory (DFT). The doping is achieved by an argon (Ar) plasma treatment of Al₂O₃ deposited onto the SnO _x film, in which the Al₂O₃ provides both the surface passivation and Al doping source. Experimental results show a wide V _th modulation range (6.08 to −19.77 V) and notable mobility enhancement (11.56 cm²V⁻¹s⁻¹) in the SnO _x TFTs after the Al doping by Ar plasma. DFT results reveal that the most possible positions of Al in SnO and SnO₂ segments are the compensation to Sn vacancy and interstitial. The compensation will create an n-type doping effect and improve the hole carrier transport by reducing the hole effective mass (m _h*), which is responsible for the device performance variation, while the interstitial in the SnO₂ segment can hardly affect the valence transport of the film. The defect compensation is suitable for the electronic property modulation of SnO towards the high-performance CMOS application.