Direct and indirect band gap semiconductors pdf

In a DBG semiconductor, direct recombination takes place with the release of the energy equal to the energy difference between the recombining particles. The probability of radiative recombination is high in the case of DBG semiconductors. Hence the efficiency factor of a DBG semiconductor is high. The photon emitted when an electron transits from the bottom of conduction band to top of valence band falls into the visible light range.

However, in case of Indirect Bandgap semiconductors, the photon emitted does not fall into the visible light range. So, energy is released as heat along with light. Band Gap: The minimum energy difference between the top of the valence band and the bottom of the conduction band is known as the bandgap. Indirect Band Gap Semiconductor: In the IBG semiconductor, the maximum energy of the valence band occurs at a different value of momentum to the minimum in the conduction band energy.

If one makes an LED in a semiconductor with a direct bandgap of 2. A particular green LED emits light of wavelength o A. Start Learning. An indirect band gap semiconductor A direct band gap semiconductor A wide band gap semiconductor A narrow band gap semiconductor. Commonly available colors of LED are red, green, blue, yellow, amber, and white. It is the conversion of electrical energy into light energy. Skip carousel. Carousel Previous. Carousel Next. What is Scribd?

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Jump to Page. However, an electron must also undergo a significant change in its momentum for a photon of energy E g to produce an electron-hole pair in an indirect band gap semiconductor.

This is possible, but it requires such an electron to interact not only with the photon to gain energy, but also with a lattice vibration called a phonon in order to either gain or lose momentum. The indirect process proceeds at a much slower rate, as it requires three entities to intersect in order to proceed: an electron, a photon and a phonon.

This is analogous to chemical reactions, where, in a particular reaction step, a reaction between two molecules will proceed at a much greater rate than a process which involves three molecules. The same principle applies to recombination of electrons and holes to produce photons.