Diode Dark Current

November 06, 2019

It is referred to as reverse bias leakage current in non optical devices and is present in all diodes. When one applies a bias to a diode in the dark a current flows through it.

Photodetectors

200 1100nm 3 2mm Uv Enhanced Silicon Photodetector Diode Low Dark Current

8 92 400 1100nm 2 5mm Silicon Pin Photodetector Diode With

The material used to construct the photodiode also affects the dark current.

Diode dark current. One exponential looks much like another. The charge generation rate is related to specific crystallographic defects within the depletion region. Dark current is the leakage current that flows in the photodiode in the absence of light.

The dark current in the photodiode increases when temperature increases. Dark current refers to the unwanted excess leakage current of a pn junction photodiode in reverse bias when it is not exposed to light. By applying the bias electrons are injected at the n type contact into silicon.

The dark current is both temperature dependent and voltage dependent. Increasing temperature andor increasing reverse bias increases the dark current. Dark current approximately doubles for every 10 0c increase in temperature and shunt resistance tends to double for every 6 0c rise.

Diode current equation expresses the relationship between the current flowing through the diode as a function of the voltage applied across it. With lights off when applying reverse bias a small reverse saturation current appears which can be easily measured. I want to measure the dark current in photoconductive mode.

How do they flow through the diode. Even in the absence of noise there is a wealth of information in comparing the illuminated and dark iv curves. Dark iv curve with a linear scale.

When operating in a photoconductive mode there tends to be a higher dark current that varies directly with temperature. Dark current dark current is leakage current that flows when a bias voltage is applied to a photodiode. Ideal diode has no current in the reverse direction.

A simple dark iv measurement produces the exponential curve so characteristic of a diode. Mathematically it is given as where i is the current flowing through the diode i0 is the dark saturation current q is the charge on the electron v. To first order for a given spectral distribution the photocurrent is linearly proportional to the irradiance.

The dark current serves as a baseline current that cannot be avoided. In the case of a photodiode this leakage current is called the dark current the current the photodiode produces with no light hitting the diode. The total current through the photodiode is the sum of the dark current current that is generated in the absence of light and the photocurrent so the dark current must be minimized to maximize the sensitivity of the device.

Physically dark current is due to the random generation of electrons and holes within the depletion region of the device. Such a diode is built to produce a current proportional to light that strikes it. A solar cell in the dark is a large flat diode.