MODULE 3

Light-Semiconductor Interaction

3.1 Optical transitions in bulk semiconductors: absorption, spontaneous emission, and stimulated emission

• In semiconductors electrons can make transitions between two energy states and create or extinguish photons in the process.  
• In particular, transitions between the conduction band (EC) and the valence band ( EV) are optically active, as the lower conduction band generally consists of s-like states while the upper valence band contains of p-like states.  
• Spontaneous emission, absorption, and stimulated emission can all take place between conduction band (EC) states and valence band (EV) states.

3.2 Joint density of states

 for a direct band gap

 for an indirect band gap

Where,
        I0 and c -- The constants.
        E -- The energy loss

3.3 Density of states for photons

3.4 Transition rates (Fermi's golden rule)

3.5 Optical loss and gain; Photovoltaic effect, Exciton

3.6 Drude model.

References:

1.J.Singh, Semiconductor Optoelectronics: Physics and Technology, McGraw-HillInc.(1995).

2.B.E.A .Saleh and M. C.Teich, Fundamentals of Photonics, John Wiley &Sons, Inc.,(2007).

3.S.M.Sze, Semiconductor Devices: Physicsand Technology, Wiley(2008).

4.A.Yariv and P.Yeh, Photonics: Optical Electronic sin Modern Communications ,Oxford University Press, New York(2007).

5.P.Bhattacharya, Semiconductor Optoelectronic Devices ,Prentice Hall of India(1997).

6. Engineering Physics by Dattu R Joshi, McGraw hill Publications.