Intercalation-Enhanced Light-Matter Interactions in MoS₂: Comparing Copper to Tin

Intercalation spans a vast space for modifying the properties of materials and provides a laboratory for studying fundamental chemical and physical phenomena on the atomic scale. Here, we present the cases of zero-valent copper and tin intercalation in MoS₂ as employed by the Koski method. We show that in both cases the host MoS₂ remains semiconducting even at the limit of high metal content. The spectrally broad and high cross section of the metals enhances the interaction of intercalated MoS₂ with light and its photodetection capabilities. This results in highly responsive devices at a broad spectral range. However, the two cases fall under different enhancement mechanisms, representing the difference in the atomic species properties as well as the packing structure and density of the intercalants within the van der Waals gap: while tin organizes in small clusters, copper intercalants organize in continuous, extended layers between those of MoS₂.  While copper features a strong plasmon resonance, tin clusters tend to ionize by contributing electrons to the conduction band of the MoS₂ hybrid. We also compare the spectral response to the two hybrids, showing a redshift towards the infrared in the photoconductivity of Sn:MoS₂.