Charge transfer element

PURPOSE:To enlarge the maximum charge transfer quantity of a charge transfer element by a method wherein a well of electric potential distribution in the condition existing no free electron is made as deep. CONSTITUTION:A p type impurity diffusion region 10 of the samely conductive type with a semiconductor substrate is formed on the whole surface of an n type impurity diffusion region 2 of the inversely conductive type to the substrate. Impurity concentration and thickness of the layer of the impurity diffusion region 10 is so instituted as when the impurity diffusion region 2 is in the minimum potential condition being completely depleted, namely in the minimum voltage in order to have no existence of free electron in the n type region 2, the impurity diffusion region 10 is to be depleted completely at the same time.