OPTICAL PROPERTIES: BULK GaAs AND RELATED MATERIALS

Abstract

This chapter is concerned with the basic optical properties of bulk semiconductors such as refraction, absorption, and dispersion as they result from lattice bivronic and electronic excitations in the semiconductors. The complex dielectric function e(co) = 6i(co) + ie^co)can now describe the optical properties of the medium at all photon energies E=rico. Real (e,) and imaginary (e^) parts of the dielectric function are connected by the well-known Kramers-Kronig (KK) relations: 1The complex refractive index n*(co)=n(to)+ik(a)) is given by n*(co)=n(co)+ik(co) = [e^co) + i^co)]" 2 (11.3)where n(co) is the ordinary (real) refractive index and k(w) is the extinction coefficient, also called the attenuation index. The optical constants n(co) and k(oo) are real and positive numbers and can be determined by optical measurements. From Eqs. (11.1) and 336 GaAs and Related Materials Downloaded from www.worldscientific.com by UNIVERSITY OF BIRMINGHAM on 08/24/15. For personal use only. e(co) u)TO-o) 2 -i(OY V J (11.8) GaAs and Related Materials Downloaded from www.worldscientific.com by UNIVERSITY OF BIRMINGHAM on 08/24/15. For personal use only. GaAs and Related Materials Downloaded from www.worldscientific.com by UNIVERSITY OF BIRMINGHAM on 08/24/15. For personal use only. * ( E) = I dS _ (11.23) s |V k (E-E)| E ,-E .. E the joint-density-of-states function measuring the product density of full and empty states of equal energy difference. The e^E) can, then, be simply written as ^^IP^PUE) (11-24) GaAs and Related Materials Downloaded from www.worldscientific.com by UNIVERSITY OF BIRMINGHAM on 08/24/15. For personal use only. ID , is expressed by a c c E GaAs and Related Materials Downloaded from www.worldscientific.com by UNIVERSITY OF BIRMINGHAM on 08/24/15. For personal use only.