Over the last decade, there has been flurry of research in the field of layered two dimensional materials,
with an increasing scientific interest and motivation from the promise of these materials for future
technologies. Beyond the discoveries of unique properties and exotic phenomena in individual materials,
the scientific interest has progressed also to heterostructures that combine several materials in a stacking
sequence. Such stacking sequences bear several degrees of freedom including rotational angle between
layers. Heterostructures span a large combinatorial space that may enable to construct new functional
materials, by design of their atomic layers sequence.
An interesting analogue to this concept is intercalation, where guest atoms are introduced into the space
between adjunct layers, forming atomically thin islands or complete layers, bridging the layers of the
original compound. Intercalation processes have been studied for a long time and are the technological
foundation of modern energy storage devices. However, the field is still in its infancy as far as electronic
and optical properties are concerned and with the aim of constructing electronic devices.
Here, we show that metal intercalation can form small clusters or continuous layers within the lamellar
van der Waals gap, depending on the properties of the metal guest atoms. We describe the device
characteristics of Li, Cu and Sn intercalated MoS2, the spectral response, photoconductive gain and
discuss the mechanism of gain in each case.