Opportunities and Challenges of 2D p‐Type Semiconductors: From Material Systems to Electronic and Optoelectronic Device Applications

ABSTRACT Two‐dimensional (2D) semiconductor materials are among the best candidates for maintaining Moore's Law. Due to their atomic‐scale thickness, high carrier mobility, and excellent gate control, 2D materials have become a significant area of research. However, intense electron doping caused by interfacial charge impurities and structural defects has led to many more reports of n‐type 2D semiconductors than p‐type. Moreover, p‐type 2D semiconductors face significant challenges, including inferior environmental stability of both materials and devices, and the difficulty of achieving high‐quality, controllable wafer‐scale synthesis. This paper reviews the latest progress in p‐type 2D semiconductors and their applications across various fields. We categorize them by type, such as monoelemental materials, chalcogenides, and oxides. First, we summarize relevant theoretical calculations, explore their hole‐dominated conduction mechanisms, and list several promising high‐quality new p‐type 2D semiconductors. Next, we review various synthesis and preparation methods for p‐type 2D semiconductors, including both top‐down and bottom‐up techniques such as mechanical exfoliation, liquid‐phase exfoliation, chemical vapor deposition, atomic layer deposition, and molecular beam epitaxy. We compare the advantages and disadvantages of each method. Then, we highlight several prototype device studies based on p‐type 2D semiconductors. Finally, we discuss their applications across various fields, including logic circuits, optoelectronic imaging, neuromorphic visual computing, and chemical/biological sensors. We also examine their opportunities, challenges, and prospects, and propose various research directions and technical pathways to advance their development. We hope this review will serve as a valuable resource for the future development of p‐type 2D semiconductors.