Ferroelectric Properties in Piezoelectric Semiconductor Zn 1-xMxO (M=Li, Mg)

Ferroelectric properties and the effect of Li+ and Mg2+ dopants in II–VI semiconductor ZnO were studied. The ferroelectric D–E loops were observed in Zn1-x (Li0.02·Mg x-0.02)O, as well as in Zn1-x LixO. The transition temperature (T c) increases in proportion to the concentration of Mg2+ ions, while it is almost constant (330 K) in Zn1-x LixO above x > 0.1. T c was 260 K for Zn0.9(Li0.02Mg0.08)O and 360 K for Zn0.7(Li0.02Mg0.28)O. An additional 20% of Mg increases T c by 100 K. The ferroelectric phase transition is strongly influenced by the introduction of small Li and Mg atoms instead of the host Zn atoms in wurtzite ZnO.