Fabrication of Zn1-xMgxO/AgyO heterojunction diodes by mist CVD at atmospheric pressure

Abstract

We report on the preparation of heterojunction based on Zn1-xMgxO/p-AgyO semiconductor heterostructure. A series of multi-layers, containing Zn1-xMgxO (ZnMgO) films stacked on InSnO (ITO) films, were prepared using mist chemical vapor deposition system with different flow rates for the Mg carrier gas/dilution gas (c.g./d.g.). AgyO films then were deposited on the ZnMgO/ITO substrates. It was found that as the flow rate of the Mg c.g./d.g. increased, the morphology and crystallinity of the ZnMgO films were extensively impacted by the Mg content and the cross-section images of the ZnMgO/AgyO HJDs showed spontaneous order of the random alloys and partial inclinations of the multi-layers, the band gaps of ZnMgO broadened from 3.3 to 3.7 eV, and resistivity increased to 1.58 × 108 Ω·cm; the work function of AgyO films increased to 5.6 eV at the highest O2 flow rate (R[O2] = 30%) during the sputtering process. Although the energy gap variations caused abrupt interfaces, these ZnMgO/AgyO HJDs demonstrated rectifying behavior with a barrier height of around 0.98 eV, which is comparable to that achieved using similar but more expensive preparation methods.