Heterointerfaces of stable and metastable ZnO phases

Thermodynamically ZnO is a prototype material which stabilizes with stable and metastable wurtzite and zincblende phases. In principle, the phase stability of ZnO depends on many parameters; however, heterointerface plays a significant role in controlling the ZnO crystalline structures. ZnO/SiC and ZnO/ZnS heterointerfaces have been studied where ZnO layers grow along the out-of-plane with an epitaxial relationship of (0 0 0 1) _ZnO ∥(0 0 01) _SiC , [ 1 1 over(2, ̄) 0 ] _ZnO ∥ [ 1 1 over(2, ̄) 0 ] _SiC and [1 1 0] _ZnO ∥[1 1 0] _GaAs , [ 1 over(1, ̄) 0 ] _ZnO ∥ [ 1 over(1, ̄) 0 ] _GaAs , respectively. Although both the ZnO phases grew uniaxially with the substrates, thin-interlayer and imbalanced charge distribution were observed in the ZnO/SiC heterointerfaces, while the ZnO/GaAs heterointerface was dominant with stacking faults and phase coexistence in lattice matrix, together with the common misfit-dislocations. Photoluminescence showed a significant bandgap energy difference in ZnO phases by ∼60 meV, and higher electron mobility in the zincblende ZnO material.