| 摘要 |
A highly sensitive and wide spectra-range mesa type photodetector having the impurity diffusion along the mesa-sidewall is provided. A mesa-type hetero-bipolar phototransistor or photodiode having a photo-absorption layer formed by a first semiconductor layer of a first conductivity type, an anode layer (or base layer) formed by a second semiconductor layer of a second conductivity type which has an opposite polarity with the first conductivity type, a wide band gap emitter or window layer formed by the third semiconductor layer on the anode layer, and the wide band gap buffer layer of the first conductivity type which has a relatively wide band gap semiconductor as compared with the second semiconductor layer on the substrate, which also serves as the cathode layer. And the first semiconductor layer, the second semiconductor layer and the wide band gap emitter or window layer is selectively etched to form the mesa structure. The diffusion region shaped like a ring in plan view is also provided from the exposed sidewall of this mesa structure toward the center of the device by a predetermined horizontal width, converted into the second conductivity type, which is the same conductivity type as the second semiconductor layer.
|
