氧化鋅變阻器之缺陷研究

Abstract

本研究利用深能階暫態量測系統研究分析氧化鋅變阻器之缺陷,量測 到三個多數載子缺陷分別定義為L1,L2,L3以及一個少數載子缺陷定義為Y. L1,L2之活化能分別是0.13eV及0.23eV,在不同添加物系統中皆穩定存在, 推論可能和氧空缺有關,應屬於本質單能階塊材缺陷.L3之活化能介於0.5 ∼ 0.75 eV之間,缺陷能接受燒結溫度及添加劑之影響,劣化之後缺陷濃度 亦有明顯的變化,屬於本質介面缺陷.Y缺陷之活化能介於0.9 ∼ 1.1 eV之 間,缺陷也受燒結環境及劣化之影響,應屬於本質介面缺陷並趨近於單能階 缺陷,而且可能與鋅空位有關連. In this research, Deep level transient spectroscopy measurement was employed to identify the activation energies and capture cross-sectionalareas for the trapping levels associated with the electronic defect present in the ZnO varistors. Three majority carrier traps (L1,L2,L3) and one minority carrier trap (Y) were observed. Two separate bulk states were observed. L1 and L2 are related to native states. A grain-boundary interface state was detected at approximately 0.5 ∼ 0.75 eV below the conduction-band edge. After the degradation, the density of the L3 trap was decreased. The L3 defect may be the interface states.The Y trap is a minority carrier trap and related to Vo. The minority carrier trap is possible due to the interface states at ZnO-ZnO grain boundaries.