Fabrication and opto-electrical properties of amorphous (Zn, B) O thin film by pulsed laser deposition

Abstract

Growth of amorphous ZnO by B doping and their opto-electrical properties are reported. The B-doped ZnO (ZnO:B) films were grown by pulsed laser deposition using polycrystalline ZnO:B ceramic targets. Although the solubility limit of B in bulk ZnO polycrystal was similar to 4%, 18%-doped ZnO:B showed the shrinkage in the c-axis length. Preferentially (002)-oriented polycrystalline ZnO:B films were grown for the B concentration [B] <= 18%; while, amorphous ZnO:B films were obtained for [B] similar to 26%. It was found that the density of the amorphous ZnO:B film was smaller by 9% than that of crystalline ZnO (5.61 g.cm(-3)), which is explained mainly by the incorporation of the light B atoms. The optical bandgap of the ZnO:B films increased with [B] and that of the amorphous ZnO:B film was similar to 3.38 eV. The amorphous ZnO:B films have low free electron density of similar to 10(15) cm(-3), suggesting the existence of electron traps. Hall mobility of the amorphous ZnO:B [similar to 1 cm(2)(V.s)(-1)] was smaller than those of the polycrystalline ZnO:B films. (C) 2015 The Ceramic Society of Japan. All rights reserved.