An object of the present invention is to clarify unelucidated aspects in the control mechanism of circadian rhythms. In one particular exemplary embodiment, the technique may be achieved using a mask for processing the substrate. The display unit includes a panel which is sealed, with liquid crystal being charged between an upper substrate and a lower substrate. A further region can extend from the buried layer, for example, to the surface of the semiconductor substrate, the buried layer and further region in combination acting as a shield to prevent minority carriers from penetrating to the device elements.