# What is Photocurrent: Definition and 15 Discussions

Photocurrent is the electric current through a photosensitive device, such as a photodiode, as the result of exposure to radiant power. The photocurrent may occur as a result of the photoelectric, photoemissive, or photovoltaic effect. The photocurrent may be enhanced by internal gain caused by interaction among ions and photons under the influence of applied fields, such as occurs in an avalanche photodiode (APD).
When a suitable radiation is used, the photoelectric current is directly proportional to intensity of radiation and increases with the increase in accelerating potential till the stage is reached when photo-current becomes maximum and does not increase with further increase in accelerating potential. The highest (maximum) value of the photo-current is called saturation current. The value of retarding potential at which photo-current becomes zero is called cut-off voltage or stopping potential for the given frequency of the incident ray.

View More On Wikipedia.org
1. ### A The main charge carrier in the ionic crystal is polaron or conduction?

Suppose I have a perfect crystal(e.g.TiO2-Rutile, band gap=3ev), under UV light, there should photoconductivity, according to the condensed matter theory, some of these excited conduction band electrons would form small polarons, I am wondering how many percent of the free conduction band...
2. ### Why in this short circuit geometry can I not sense a photocurrent?

Hi, I'm wondering why shorted circuit geometry like figure 2 did not sense photocurrent? Even if the the circuit composed like 2, I guess that by the Kirchhoff's Law, voltage should apply to the ampere meter and photocurrent should be sensed. But in real experiment, I found that shorted circuit...
3. ### I Photodiode bandwidth: why does power decrease with frequency

Hi, I'm studying p-i-n photodiode (PD) at the moment and understand that the photodiode's response will depend on the frequency of the light signal going into it. I am struggling however to understand the concept of bandwidth, and why is it that the photocurrent at the PD decreases with higher...
4. ### Does charging metal negatively decrease the work function?

Since positive charge on the photocatode increases work function of electrons, does charging metal photocatode negatively decrease work function? If not, why?
5. ### The effect on a photocurrent of reducing the frequency of photons

Homework Statement Homework EquationsThe Attempt at a Solution As frequency is decreased to threshold, no. of emitted electrons will remain same, but their maximum kinetic energy will decrease. So, the current should decrease slowly. For frequency less than the threshold frequency, no...
6. ### Cameras detecting Infrared and making it visible

Hi All, It is known that ordinary cameras can make infrared radiation which comes from remote controls visible at their own display. My question is about the explanation of this fact. Is the electronic process simple to describe? It seems that the infrared can produce photocurrents which are...
7. ### Equation for photocurrent dep. wavelength, diffusion length,

Hey, I’m currently stuck at my research and I’d like to ask for some help. First I’ll try to introduce the measurement and the setup and then I’ll get straight to the problem. The goal is determining the diffusion length of charge carriers quantitatively in different materials. For this...
8. ### Variation of saturation photocurrent with intensity

1. In photoelectric experiment, if anode potential w.r.t. cathode is increased, photocurrent first increases then becomes a constant, since all the photoelctorns ejected from cathode are collected at anode. If we increase the intensity of light at this point, the 'saturation current' increases...
9. ### Radiometry, photocurrent in optics simulation

Hi all, I have to estimate a photocurrent produced in the following simulation setup. Photodiode (detector) and LED (spaced 2cm) lie on one axis, oriented toward a wall (radiometer film) which is parallel to the axis and at a distance of about 10cm from the axis. How much photocurrent would an...
10. ### Photocurrent and frequency of incident light

Why is photocurrent in the photoelectric effect independent of the incident frequency of light after the threshold frequency? If more frequency means more kinetic energy of electrons, then doesn't that mean that there should be more electrons passing a cross-section of the metal tube per second...
11. ### Photocurrent shot noise correlation function

Hi I have stumpled upon the following expression for the correlation function of the photocurrent shot noise for a photodiode <\delta i(t)\delta i(t+\tau)> = \frac{e^2\eta}{h\nu}P\delta(\tau) where η is the quantum efficiency and P the power in the signal. δ(τ) denotes the Dirac delta, which...
12. ### How do I accurately measure short circuit photocurrent?

In my phototelectrochemical setup I have a working electrode, reference electrode and a counter electrode . Now I need to measure the short circuit photocurrent so that I can calculate IPCE (incident photon to photocurrent efficiency). How will I measure this current ?
13. ### Maximum photocurrent ejected by electrons in photoelectric effect

Does anyone know how to determine the maximum photocurrent that could be produced by ejected electrons in a photoelectric effect experiment_(as unpolarized beam of light incidents on a metal surface)? I don't know of any formula that calculates the photocurrent and I could not derive any. I...
14. ### Photoelectric effect and photocurrent drop

Homework Statement Does the photocurrent drop to zero when a potential across it is equal to the kinetic energy of electrons?, because i found this not to be the case, the photocurrent reached a steady value that didnt decrease further, as i increased the potential across the anode and...
15. J

### Maximum photocurrent in photoelectric effect

I would like to know why, experimentaly, there is a difference between the maximum photocurrent with a yellow illumination (lambda = 580 nm) and other colors with a lower wavelenght like green or blue, respectively 546 and 404 nm. According to the theory, the max photocurrent does not depend of...