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10 lessons,
1h 13m
Photoconductivity -1
200 plays

Introduction of photoconductivity

Diksha kindo
law Student. science student .love to teach physics. BA-LLB. work as a free lancer at unacademy

Unacademy user
mam actually you are reading book plzz explain
Vanmala Ramesh
2 months ago
Megha I always explain everything in detail please watch the lessons
  1. * Semiconductor Bandgaps E are usually in the range: 0E 3 eV (up to 6 eV if diamond is included) Also, at equilibrium, at temperature T = 0. the valence band is full &the conduction band is empty Now, consider what happens if electromagnetic radiation ("light") is shined on the material. In the photon representation of this radiation Ifhv 2 Eg some electrons can be promoted to the conduction band leaving some holes in the valence band

  2. Now. consider some of the yarious possible tvpes of spectra associated with this process: Looks at the number of absorbed photons (intensity) vs. photon frequency Looks at the number of retlected photons (intensity) vs photon frequency o Looks at the number of transmitted photons (intensity) Absorption Reflection anssio Looks at the numb vs. photon frequency Emission Looks at the number of emitted photons (intensity vs. photon frequency o

  3. A (non-comprehensive) list of Various Spectra Types: Absorption, Reflection, Transmission, Emission Each of these types of spectra is very rich, complicated, & varied! . Understanding such spectra gives huge amounts of information about: electronic energy bands, vibrational properties, defects,

  4. Interaction Between Light & Bulk Material Many different possible processes can occur! 1. Refraction 2. Transmission 3. Reflection "Semi- transparent" material Incident light a. Specular b. Total internal c. Diffused 4. Scattering There is also Dispersion where different colors bend differently

  5. Light Interaction with Solids Reflected: IR Absorbed: A Transmitted: IT Incident: lo Optical Classification Tran pare hear strain 6 tsarainh Opaque 1816 HK'nit, (12.7)

  6. A Quick Review of Light" & Photons History: Newton & Huygens on Light Light as waves * Light as particles Christiaan Huygens Threy strongly disagreedwith each other

  7. Light Einstein & Planck 1905 Einstein Related the wave & particle properties of light when he looked at the Photoelectric Effect. .Planck Solved the black body radiation problem by making the (first ever) quantum hypothesis: Light is quantized into quanta (photons) of energy E hv. Wave-Particle dualiy (particles) waves) Light is emitted in multiples of a certain minimum energy unit. The size of the unit tie photon. Explains how an electron can be emitted if light is shined on a metal The energy of the light is not spread but propagates .