Question

A sample of semiconductor has a cross sectional area of 1 cm^2 and a thickness of 0.1 cm. Determine the number of electron-hole pairs that are generated per unit volume per unit time by the uniform absorption of 1 watt of light at a wavelength of 6300 Angstrom. Assume each photon creates one electron-hole pair.

Answer 1

Answer:

(a)

Calculate energy of one photon.

Here  is the Plank’s constant,  is the velocity of light and  is the wavelength.

Substitute  for  and .

State the conversion factor.

Calculate volume.

Here  is the area of the cross section and  is the thickness of the sample.

Substitute  for  and  for  .

Calculate the number of electron hole pair.

Here  is the power and  is the volume.

Substitute  for  and  for 

Hence the number of electron hole pair generated per unit volume per unit time is