| 摘要 |
PROBLEM TO BE SOLVED: To lessen the saturation current at the time of no photoirradiation of a pn junction and to increase an output voltage by providing a third layer in addition made out of a material having a larger band gap than the semiconductor material of the pn junction, on the interface of this junction. SOLUTION: A third layer 15 made out of a material having a larger band gap than a semiconductor material for making the pn junction of a solar cell, on the interface of this junction. Since the band gap of the third layer 15 is 1.95eV, and is larger than the band gap 1.43eV of a semiconductor layer forming the pn junction, a saturation current flowing under a reversely biased condition at the time of no incident rays is reduced. But, if the film thickness of the third layer 15 is thicker than a certain extent, it decreases the saturation current, and prevents electrons and holes generated by photoabsorption from diffusing into p-type and n-type layers. Consequently, it becomes possible for electrons and holes to pass the third layer 15 well by the tunnel effect, if the film tltickness is set to a favorable value of 5.0nm. |
