The conductivity through the (001) direction depends on a combination of the thickness of the (001) bulk and the degree of surface depletion layer thickness. In large particles, conduction is dominated by the bulk, with only a minor contribution from the more resistive surface depletion layer, caused by electron donation into the SnO. In smaller particles/high surface areas, this conduction is dominated by the depletion layer, either by narrowing the bulk area or by complete depletion. This effect is exaggerated in the (101) plane due to its smaller dimension, resulting in effective depletion layer formation, and the granular network morphology ensuring conduction must be mediated through interfaces between (101) planes.