MoS2|ZnO isotype heterostructure diode: Carrier transport and band alignment

Molybdenum disulfide (MoS2) is one of the most studied semiconducting materials among the class of layered transition metal dichalcogenides (TMDCs). Though there has been an intense focus on its monolayers, multilayer MoS2 (m-MoS2) also offers applications owing to its indirect bandgap and relatively high carrier mobility. Specifically, there has been sporadic use of its heterostructures as in MoS2|ZnO, but so far, there is no systematic characterization to unravel the physics of such prototypical heterostructures. Here, we report results on an n-n+ isotype heterostructure diode with the Au|m-MoS2|ZnO device structure to study the role of the hetero-interface in determining its electrical characteristics. The isotype heterostructure device exhibits rectification ratio of the order of 10(3) over the measured temperature range of 19-300 K. Temperature dependent current-voltage (J-V) characteristics show that while tunneling is dominant at low temperature, diffusion mechanism controls the charge transport in the high temperature regime. The barrier height due to band alignment at the interface is found to have Gaussian distribution with a mean energy of 0.95 eV. We also report charge carrier freeze out due to de-ionization of the dominant donor in MoS2 at a characteristic temperature of similar to 37 K, which correlates with features of both J-V and C-V characteristics. The proposed heterostructure diode facilitates electrical as well as optical characterization of multilayer TMDCs.

Automated summary

Molybdenum disulfide (MoS2) is a highly studied semiconducting material, with both monolayer and multilayer forms showing potential applications. Heterostructures, such as the Au|m-MoS2|ZnO device, play a key role in determining the electrical characteristics of these materials, offering insights into their behavior at different temperatures and charge transport mechanisms. This research highlights the importance of heterostructure diodes in facilitating the electrical and optical characterization of multilayer TMDCs.