Two-dimensional (2D) MoS 2 was grown on AlGaN(GaN) substrates by chemical vapor deposition (CVD) and 2D-3D MoS 2 -AlGaN(GaN) heterostructures were formed. The MoS 2 crystal on AlGaN surface has a mixed and irregular shape including single and multiple layers, while the single layer of triangular MoS 2 is basically prepared on GaN surface. Combined with theoretical first-principles analysis, it is found the adsorption of AlGaN to MoS 2 is lower than that of GaN, which leads to the deposition of MoS 2 molecules on AlGaN surface, forming multilayer shapes. In addition, Both the MoS 2 -AlGaN(GaN) heterostructures exhibit indirect band gaps and broad-band light absorption performances. Index Terms-Chemical vapor deposition, GaN substrate, heterostructure, two-dimensional MoS 2 . I. INTRODUCTIONA S ONE of the important members of two-dimensional (2D) transition metal chalcogenides, 2D semiconducting MoS 2 has high carrier mobility, excellent chemical stability and thermodynamic stability, which is very suitable for electronic and optoelectronic device applications [1], [2]. Since there is usually van der Waals (vdW) force between 2D MoS 2 layers, integrating it with other different semiconductor materials and constructing Manuscript

To improve the performances of AlGaN solar‐blind ultraviolet (UV) avalanche photodetectors (APDs), we propose a separate absorption and multiplication (SAM) AlGaN APD with a gradually doped charge layer. The calculation results indicate that the designed APD can significantly increase the maximum gain by almost 40%, and reduce the breakdown voltage by about 9% compared with the conventional AlGaN APD. The parameters of multiplication layer and p‐type layer are optimized, and the physical mechanism is described in detail, which provides theoretical guidance for high‐performance device structure design and experimental preparation.