Studies of CCDs for Vertex detector application

In this paper we summarize the research activities at the JLC Vertex group. A simulation study of the vertex detector performance has started, which has as a goal optimization of its design. Attention has been paid to the mechanical distortions of CCD chips and their supporting ladders, caused by cooling. Laser measurement system to investigate the distortions has been assembled and preliminary measurements on CCDs have been obtained. Radiation damage effects on CCDs have been extensively studied and some important conclusions on preferable device structure and operation conditions has been drawn. A study of charge sharing between the CCD pixels, which is important in particle detector applications, is also under way.