| 摘要 |
The invention relates to a colour sensor based on semiconductor photodiodes for differentiating between two wavelength regions situated between 300 and 800 nm. In the sensor, the photodiode (9) has a p-i-n layer structure (3, 4, 5) whose i-type layer (4) has a light (soft) p- or n-doping (p-s-n diode) and which, with a given voltage applied to the diode in the forward direction, generates a photocurrent having a direction which depends on the direction of incidence of the light (from the p-type or n-type side) when light (17) of the shorter-wave wavelength region is incident. In the i-type layer, this current direction undergoes a reversal between 400 and 600nm on changing to the longer-wave wavelength region. In the diode (9), which is preferably made of amorphous, hydrogenised silicon (a-Si:H) with a thin-film structure, the limit of the wavelength regions and the sensitivity to red or blue light can be adjusted by varying the applied voltage in the range from 0.5 to 0.9 volts. The properties of the p-s-n diode can be adapted to a specific application purpose by means of fine doping of the i-type layer (4) (p-type or n-type) with or without doping profile. When built into a suitable electrical circuit as colour sensor, the p-s-n diode (9) exhibits a high sensitivity, has a simple structure (without additional colour filters) and has a sharp transition point on changing from one wavelength region to the other. In addition ... Original abstract incomplete. <IMAGE>
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