In Situ Study Of The Electronic Structure Of Polar-To-Polar Srtio3/(000(1)Over-Bar)Zno Heterointerface

The SrTiO3(STO)/ZnO heterointerface, which is widely used in the fabrication of novel optoelectronic devices, is a classical system combining functional perovskite oxides and wurtzite-structure semiconductor materials. The electronic structure of the heterointerface often plays a significant role in controlling the functions of novel devices. In this study, the electronic structure was explored using in situ photoemission spectroscopy and X-ray absorption spectroscopy. X-ray diffraction results showed the coexistence of (111)(STO) and (011)(STO) orientations for the STO film deposited on the ZnO-(000 (1) over bar) substrate via pulsed laser deposition. High-resolution transmission electron microscopic results revealed two types of polar interfaces: [11 $$(2) over bar][10 $$(1) over bar](111)(STO)//[1 (2) over bar 10][10 (1) over bar0] (000 (1) over bar)(ZnO) and [111][2 (11) over bar](0 1 1)(STO)//[10 (2) over bar1][10 (1) over bar0](000 (1) over bar)(ZnO). In situ photoemission spectroscopic results revealed downward band bending and the transformation of the valence states of Ti from 4+ to 3+, with extra electrons transferring to the hybridization states between O 2p and Ti t(2g) orbitals at the polar-to-polar STO/ZnO interface. We propose that the polar discontinuity drives the electron transfer to the STO/ZnO interface during the growth process. This study provides insight into the electronic structure of the STO/(000 (1) over bar )ZnO heterointerface.