People use photodiodes as single devices after integrating a single photodiode in one casing. However, there are PIN photodiode arrays that people have to place thousands of photodiodes on a single chip. These are one-dimensional arrays. However, people can also find square shapes or even two-dimensional shapes.
There may be added electronic elements in a photodiode chip regarding the photocurrent signals amplification. Users can only find the photodiodes in a chip in the simplest situation. However, all cathodes may connect to a typical pin and the anodes to separate pins. Most PIN photodiode arrays may not contain additional optical elements; some have microlenses, apart from potential anti-reflection coating. With this, users can collect more light from a specific direction.
The general words are focal plane arrays or PIN photodiode array. In principle, operators can integrate other photodetector types, even though the typical ones are photodiodes. Operators can find other specialized driver circuits that they can connect to PIN photodiode arrays.
They typically read out the individual photodiodes signals in contrast to a CCD or CMOS sensor chip. Using very high speeds, this approach allows for signal readout.
PIN Photodiode Arrays Applications
Here are some explanations of the typical PIN photodiode arrays:
- With the combination of PIN photodiode arrays with a scintillator crystal, operators can acquire a spatially resolving gamma radiation or X-rays detector, as needed for industrial inspection purposes.
- A PIN photodiode array can operate as an optical spectrograph when combined with a diffraction grating, sending several wavelength components to other diodes. Users use this principle in optical coherence tomography compact apparatuses.
- When the users scan a one-dimensional array in the ‘viewing direction,’ they will obtain two-dimensional images with speed similar to that of the two-dimensional CMOS sensors. As an option, operators can use a two-dimensional photodiode array.
- Users can use this device as a position sensor. They can infer a laser beam, a light beam’s linear position, from the photocurrent distribution. Regarding small ranges of position, it will be enough to have two diodes with a balanced detector. However, with long PIN photodiode arrays, users will have position measurements in a much larger range.
PIN Photodiode Arrays Properties
There can be relevancy in PIN photodiode arrays with different properties, depending on the application.
- There are several casings for the PIN photodiode arrays with SMT/SMD type, DIP, or PCB mounts.
- The use of low electrical capacitance fast photodiodes will determine a high readout speed.
- Some applications may require a low cross-talk and a high uniformity of responsivity between pixels.
- The sensitivity and responsivity decide the quantum and size efficiency. With that, people can detect low light levels. Regarding the highest responsivities, PIN photodiode arrays with avalanche photodiodes are obtainable. Also, how the active regions are close together is vital since there can be a loss of detectable light with any dead space between them.
The obtained spectral response determines the photodiode type. The common type is silicon diodes, and operators utilize them for visible light. Those essential for infrared applications are based on germanium (Ge) photodiodes or gallium arsenide (GaAs).