出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：For the upgrade of the Belle detector at KEK DEPFET pixels (Depleted p-channel field effect transistor) are foreseen for the two innermost layers of the vertex detector. As a MOS device, the DEPFET is susceptible to ionizing radiation, which will be created near the interaction point. Ionizing radiation damages the silicon dioxide and alters the operating characteristics of the transistor. The DEPFET exhibits two gate contacts (gate and clear gate) and the final sensor may have a relatively complex pixel layout. In this layout several potential configurations for the clear gate contact exist. As the radiation damage depends not only on the dose, but also on the electric field in the gate oxide, several test structures, which correspond to different clear gate designs, have been irradiated with x-rays. This paper presents measurements and results from irradiation campaigns and show the influence of a variable silicon nitride layer deposited on top of the silicon dioxide.
