What is the principle of photoconductivity?
Photoconductivity is the tendency of a substance to conduct electricity to an extent that depends on the intensity of light-radiant energy (usually infrared transmission or visible light) striking the surface of a sample. Most semiconductor materials have this property.
What causes photoconductivity?
Photoconductivity is the increase in electrical conductivity produced by shining light on a material. A related effect, called the photovoltaic effect is the inducing of voltages by light.
What are photoconductive devices?
Devices that change their resistance upon exposure to incident radiation are called photoconducting devices. A photoconducting device or a photoconductor can also be termed a photoresistor, photoconductive cell, or a photocell. Photoconductivity was first observed in selenium more than 100 years ago.
Which one is a photoconductor?
Intrinsic photoconductor materials include lead sulfide, lead selenide, cadmium sulfide, and mercury cadmium telluride, while germanium and silicon are the usual hosts for extrinsic photoconductors with impurities such as arsenic, copper, gold, and indium.
Why CdS is used in photoconductivity?
A low resistivity and a high photosensitivity are required for photoconductive-sensor applications. The band gap of CdS is in the range of visible light and the photosensitivity in the visible range is very high for CdS films.
How do you measure photoconductivity?
Experimental Methodology
- Check the ohm law in the contacts in the dark.
- Measure the residual conductivity (residual or dark current Io)
- Measure the steady state photoconductivity for each wavelength.
- Measure the lamp signal for each wavelength, correct according to the detector response (using a rule of three)
What is photoconductivity explain principle and construction of a photovoltaic cell?
Photoconductive Cell Construction and Working – Light striking the surface of a material can provide sufficient energy to cause electrons within the material to break away from their atoms. Thus, free electrons and holes (charge carriers) are created within the material, and consequently its resistance is reduced.
What is negative photoconductivity?
In contrast to positive photoconductivity, negative photoconductivity (NPC) refers to a phenomenon that the conductivity decreases under illumination. It has novel application prospects in the field of optoelectronics, memory, and gas detection, etc.
What is photoconductor and example?
Photodiode. The material which allows photoconductivity is known as a photoconductor. It is a p–n junction device used to convert the light into current. Examples of materials used in photoconductors are selenium, conductive polymer polyvinyl carbazole, etc.
Is selenium A photoconductor?
A-Se is well developed technologically as it has been used as a photoconductor in photocopiers and also in an X-ray imaging technique known as xeroradiography for decades. It is used in its amorphous form, so amorphous selenium plates can be made by evaporation.
What is irradiance photoconductivity?
a) The photocurrent IPh as a function of voltage U at a constant irradiance Φ: The relation between the photocurrent IPh and the voltage U applied at a constant irradiance (constant angle α between the polarization planes of the filters), i.e. the current-voltage characteristics, is shown in Fig.
What is photoconductivity response time?
The reported photoconductivity response time as measured from photocurrent decay ranged from a few tens of nanoseconds to a few minutes (Misra et al., 1995; Kung et al., 1995; Binet et al., 1996a).
What is photoconductive sensor?
Photoconductive detectors are a type of photodetectors which are based on photoconductive semiconductor materials. Here, the absorption of incident light creates non-equilibrium electrical carriers, and that reduces the electrical resistance across two electrodes.
What is the difference between photoconductive cell and photodiode?
Unlike standard photodiodes, which produce a current when exposed to light, the electrical resistance of the photoconductive material is reduced when illuminated with light.
Is photodiode and photoconductor same?
Lead Sulfide (PbS) and Lead Selenide (PbSe) photoconductive detectors are widely used in detection of infrared radiation from 1000 to 4800 nm. Unlike standard photodiodes, which produce a current when exposed to light, the electrical resistance of the photoconductive material is reduced when illuminated with light.