Abstract: Indium selenide (InSe), a typical layered III-VI semiconductor, has attracted intense interest owing to its high electron mobility, tunable bandgap, and exceptional plastic deformation capability, making it a promising candidate for next-generation electronic, optoelectronic, and flexible devices. Recently, the controlled growth of intrinsic InSe crystals has been well developed, whereas systematic investigations on the preparation of doped InSe crystals remain relatively scarce. The reliable synthesis of high-quality, composition-controlled doped InSe crystals plays a key driver that urgently propelling InSe towards practical applications. In this study, intrinsic InSe crystals were first grown using the Bridgman method, and high-quality Bi-doped InSe crystals were further prepared through introducing Bi in the source material synthesis stage. Optical microscopy and scanning electron microscopy measurements indicate that the as-grown Bi-doped InSe crystals exhibit smooth surface and excellent single-crystalline characteristic. Raman spectroscopy and X-ray diffraction analyses further demonstrate that the phase structure of InSe remains consistent after Bi doping, with both intrinsic and Bi-doped crystals exhibiting the ε-InSe phase. Chemical etching experiments reveal that the introduced Bi atoms can interact with the dislocation cores within crystal, effectively suppressing their motion and resulting in a significant reduction in dislocation density. Electrical measurements show that the Bi doping markedly increases the carrier concentration and mobility of InSe crystal in the high-temperature section, which is primarily attributed to the introduction of additional free carriers, as well as the suppression of carrier scattering resulting from the reduced dislocation density. Consequently, we have successfully fabricated Bi-doped InSe crystal and verified its superior performance over the intrinsic InSe. This work provides theoretical insights and experimental guidance for optimizing the properties of InSe crystals and advancing its integration application in future devices.

Key words: InSe crystal, Bi elemental doping, Bridgman method, dislocations