1. First, the principle is different.
Photodiodes are based on the energy band theory of semiconductors. When the light irradiates the photodiode, when the energy of the light is greater than the band gap energy, the electrons in the valence electron band are excited to move to the conduction band, and the original valence electrons leave the hole. In this way, electron-hole pairs are generated in the p region, the n region and the depletion layer. Under the action of the electric field of the depletion layer, electrons accelerate to the N region, and holes accelerate to the P region, so that the P region is positively charged and the N region is negatively charged, and each of them moves (drifts) to the counter electrode, thereby generating current. Then the information of light can be obtained by detecting this current, or the current can be amplified to generate electricity, which is a solar cell.
There are two main principles of photomultiplier tube: photoelectric effect and secondary electron emission theory. First of all, the photoelectric effect, as we all know, will release electrons when light is incident on the surface of alkali metal, and will escape from the surface of metal when the kinetic energy of electrons exceeds the work function of alkali metal. At this time, if a very sensitive galvanometer is used, the current signal can be detected. The second part is amplification. After the escaped electrons are amplified by the multiplier for the second time, the current signal will increase continuously, and finally a larger current signal will be output at the anode. Compared with photomultiplier tube, photomultiplier tube can generate and amplify current, but the principle of generating current is completely different.
2. Secondly, the scope of application is different.
This is very clear. Photomultiplier tubes are generally used in weak light detection places, such as some gamma cameras, the detection of radioactive sources and so on. The application of photodiode has been simply explained in principle, so I won't repeat it here.
3. Manufacturers: Photodiodes are very common photoelectric components, so there are many manufacturers, so you can check them out. However, there are few photomultiplier tube manufacturers. The photomultiplier tubes in the world are mainly produced by one company: Hamamatsu Photon of Japan. If you are doing photoelectric detection, you should be very familiar with this company, followed by photonis in the UK. However, the company stopped production after the financial crisis.
I hope I can solve your problem!