CCD versus BBD mode for CCD with ion-implanted gaps

The gap regions of charge-coupled devices made with one-level metallization have been implanted with different doses of boron ions. Two operational modes are possible, depending on the dose of implantation. For low doses the charge of a region is completely transferred--corresponding to the CCD mode-- whereas with high doses only a fraction of the charge is transferred--which is the BBD mode. The implantation of low doses reduces disturbing potential barriers in the gap regions, whereas the implantation of high doses forms an additional p layer in the gap region of the substrate. These p layers form potential wells; the surface potential of these wells will be determined theoretically and experimentally as a function of the implantation dose. Results concerning the transfer inefficiency ε versus frequency are given for both modes of operation.