| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical sensor which utilizes light at maximum efficiency, has a high S/N ratio, is extremely reduced in size, and suitable for the conversion of infrared rays in a middle infrared range into electric signals.SOLUTION: The optical sensor at least includes a first n-type semiconductor layer 2 formed on the surface of a semiconductor substrate, a third i-type semiconductor layer 4 serving as a light-absorbing layer formed on the first semiconductor layer 2, a second p-type semiconductor layer 3 formed on the third semiconductor layer 4, a plurality of fourth semiconductor layers 5 formed between the second p-type semiconductor layer 3 and the third i-type semiconductor layer 4, and a fifth semiconductor layer 6. The band gap of the fourth semiconductor layer 5 is larger than band gaps of the second and third semiconductor layers 3 and 4. The plurality of fourth semiconductor layers 5 and the fifth semiconductor layer 6 are laminated alternately to form a superlattice structure for suppressing both a diffusion current and a leak current generated at the third semiconductor layer 4 by infrared rays. This improves an electric output for an incident light quantity, and thus improves an S/N ratio. |
