Growth of vertical type InSe/TMDs heterostructures for efficient charge transfer and nonlinear optical performance

Indium selenide (InSe) nanofilms with high carrier mobility and tunable band structure are a typical III-VI group two-dimensional semiconductor material, which has attracted extensive attention in the field of microelectronics and optoelectronic materials. However, due to a large number of interface defects and low efficiency of internal photogenerated charge separation in two-dimensional materials, it is difficult to achieve efficient photoelectric conversion and slow down the carrier decay rate. Here, a two-step magnetron sputtering method was used to synthesize ε-InSe/transition metal dichalcogenides (TMDs) (MX2: M = W, Mo; X = Se, S) heterojunctions films. The electronic transitions and exciton relaxation mechanisms in linear and nonlinear absorption of ε-InSe/TMDs heterojunctions films under light excitation were analyzed. The charge transfer and orbital contribution of ε-InSe/TMDs heterojunctions were discussed. The electromagnetic field changes of InSe/TMDs heterojunctions were simulated. The formation of type II InSe/TMDs heterostructures effectively separates photo-generated electrons and holes, increases the lifetime of carriers, and is of great significance for understanding the physical contact behavior between TMDs and TMDs semiconductors and promoting their applications in optoelectronic devices.