Reduction of fixed loss in buried-channel CCD's operating at 77 K

The authors describe studies on charge transfer loss in buried-channel charge-coupled devices (BCCD's) at 77 K. Experiments suggest that the fixed loss occurs mostly during the last transfer from phase clock to output diffusion. It is shown that this loss can be reduced by reducing the doping concentration in the buried channel and introducing a potential step in the middle of the storage well along the charge-flow direction. Transfer inefficiencies as low as 8.6*10/sup -5/ without fat zero at 3-MHz clock rate are observed at 77 K.< >