Alternating-current thin-film electro-luminescent devices: Effect of fabrication conditions on aging and failure defect formation

Abstract

Various types of failure defects can be encountered or unintentionally generated in the alternating-current thin-film electroluminescent (ACTFEL) devices by various growth, environmental, and driving conditions. The review summarizes the existing information on the failure formation and aging phenomena as well as methods of defect analysis and classification. The material reported in this paper is intended to serve as a useful tool for the new failure analyst as well as a convenient reference source for the expert in field of thin-film electroluminescent devices. In this study, different kinds of failures, such as localized destructive breakdown defects (LDBD), propagating defects, blistering, layer de-lamination, stress-induced defects, defects of packaging and metallization, and defects due to moisture and ion migration are covered. The optical observation is found to be one of the most valuable tools for large-area defect investigation. The layer-by-layer etch technique is applied to analyze the position of each type of defect in the stack. Most of these defects were found to start at the edges of the pixel. Both the material quality and uniformity of the semiconductor and insulator layers as well as quality of the front transparent electrode shoulders are found to be prerequisites of the failure defect-free structure. Some peculiarities of the active layer growth are found to be responsible for the stoichiometry perturbation and inclusion formation.