Tune the electronic structure of MoS2 homojunction for broadband photodetection

Abstract

• Nb-doped MoS2 film has been prepared and studied. • The doping electronic configuration has been revealed. • MoS2/Nb-MoS2 homojunction based phototransistor shows broadband photodetection. • The gate tunable photoresponse, detectivity and EQE has been discussed. Due to the weak absorption and low light-matter interaction of MoS 2 , intrinsic MoS 2 photodetector usually has low photoresponse, thus limiting its real application. Herein, MoS 2 homojunction was constructed by using the chemical vapor deposition grown intrinsic MoS 2 films and the Nb-doped MoS 2 films. The results show that the Nb doping will induce p -type doping in MoS 2 , where the electron concentration will decrease by 2.08 × 10 12 cm –2 after Nb doping. By investigating the photoelectric effect of MoS 2 /Nb-doped MoS 2 homojunction-based phototransistor, the tunability of the photoresponse, detectivity as the function of the external field, wavelength, and power of light have been studied in detail. The results show that the photoresponse and detectivity are strongly dependent on the gate voltage due to the external field tuned interlayer photoexcitation attributing to the band bending. The maximum of photoresponse can reach 51.4 A/W, the detectivity can reach 3.0 × 10 12 Jones, which is two orders higher than that of intrinsic MoS 2 . Furthermore, by correlating the photoresponse and detectivity with the external field, it is found that the photodetection of MoS 2 homojunction can be significantly tuned and exhibit well photodetection in infrared. This comprehensive work not only sheds light on the tunable photoexcitation mechanism but also offers a strategy to achieve a high-performance photodetector.