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There are two types of infrared receivers: photodiodes and phototransistors. Photodiodes convert light signals into electrical signals, while phototransistors also amplify electrical signals. Therefore, phototransistors are also divided into two types, namely NPN type and PNP type.

stayInfrared receiver tubeThere is a glass lens on the tube shell that allows light to enter, and the incident light passes through the lens and is precisely reflected on the tube core. The infrared acceptance diode chip is a PN junction with photosensitive properties, which is encapsulated inside the tube shell. The photosensitive surface of the infrared receiver tube core is a thin film formed on N-type single crystal silicon through diffusion technology.

Its die and PN junction area on the die are made larger, while the electrode area on the die is made smaller, and the PN junction depth is shallower than that of ordinary semiconductor diodes. These structural characteristics are all aimed at improving the ability of photoelectric conversion. In addition, like ordinary semiconductor diodes, a SiO2 maintenance layer is grown on the silicon wafer to maintain the edge of the PN junction, thereby improving the stability of the transistor and reducing dark current.

In order to accommodate more incident light over a larger area, the PN junction area of the infrared receiver tube should be made relatively large, while the electrode area should be minimized. Additionally, the depth of the PN junction is very shallow, usually less than 1 micron. The infrared receiver operates under the action of reverse voltage. When there is no light, the reverse current is very small (usually less than 0.1 microamperes), which is called dark current. When exposed to infrared light, infrared photons carrying energy enter the PN junction and transfer the energy to the bound electrons on the covalent bond, causing local electrons to break free from the covalent bond and generate electron hole pairs (referred to as photo generated carriers). They participate in drift motion under the action of reverse voltage, causing a significant increase in reverse current. The greater the intensity of light, the greater the reverse current. This characteristic is called "photoconductivity". The current generated by an infrared receiver tube under normal illumination is called photocurrent. If a load is connected to the external circuit, an electrical signal is obtained on the load, and this electrical signal changes accordingly with the variation of light.

The function of infrared receiver tube is to stop photoelectric conversion, and it is widely used in light control, infrared remote control, light detection, fiber optic communication, photoelectric coupling and other fields.