Ferroelectric Properties in Piezoelectric Semiconductor Zn_1-xM_xO (M=Li, Mg)

Abstract

Ferroelectric properties and the effect of Li + and Mg 2+ dopants in II–VI semiconductor ZnO were studied. The ferroelectric D – E loops were observed in Zn 1- x (Li 0.02 ·Mg x -0.02 )O, as well as in Zn 1- x Li x O. The transition temperature ( T c ) increases in proportion to the concentration of Mg 2+ ions, while it is almost constant (330 K) in Zn 1- x Li x O above x > 0.1. T c was 260 K for Zn 0.9 (Li 0.02 Mg 0.08 )O and 360 K for Zn 0.7 (Li 0.02 Mg 0.28 )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.