First Sensor develops and manufactures photodiodes in series covering a range of technologies.
Materials and processing can be adapted to individual customer and product requirements, thus enabling the optimization of parameters such as sensitivity at different wavelengths, speed and capacity. We will be happy to help you find the ideal technology for your application.
Spectral response, ambient temperature of 23°C
A photodiode is an active component that converts light into an electrical voltage (photovoltaic effect) or photocurrent. The p-n junction in the silicon semiconductor serves as the physical basis for this process. When photons with sufficient energy are absorbed by the detector, this results in the formation of charge carriers (electron-hole pairs), which are separated in the space-charge region and thus generate the photocurrent.
While the charge separation also occurs without the application of an external voltage, the process can be accelerated by such a reverse voltage. The photocurrent remains linear to the absorbed light volume across many orders of magnitude if the diode is not operated in a state of saturation.
Depending on the external connections, we differentiate between two different operating states: element and diode. In the case of element operation, the diode is connected directly to the consumer without the use of an external voltage source. No dark current flows in this operating state, which facilitates the detection of minimal intensities.
During diode operation, an external voltage supply is connected with the consumer in series, whereby the voltage is applied in reverse direction. This operating mode is ideal for applications in which a rapid signal response is required. The main disadvantage is the dark current, which grows exponentially with the temperature.
A PIN diode comprises a near-intrinsic semiconductor region – usually the space-charge region – sandwiched between a p-type diode and an n-type substrate. However, the term is also used for components with inverse conductivity, provided that no other non-linear effects are utilized in the component.