From ZnS nanobelts to ZnO/ZnS heterostructures: Microscopy analysis and their tunable optical property

Ultrathin ZnS nanobelts were assembled by ultrasmall nanocrystals with oriented self assembly, which were then transformed into their single-crystal counterparts by thermal treatment in N2. ZnO/ZnS heterostructures were also obtained at elevated temperature in open air, where well aligned ZnO nanocones were grown along the ZnS nanobelts with a definite orientation relationship described as [0001]ZnS∥[0001]ZnO and (101¯0)ZnS∥(101¯0)ZnO. Mixed transition and tuned band gaps of the heterostructure were experimentally observed, which was in good agreement with the theoretical predications and can be interpreted based on the model of a strained staggered type-II band structure.