Anisotropy of infrared spectral absorption in uniaxiallystressed nGaP
Abstract
A theoretical and experimental investigation of freecarrier absorption (FCA) in unstressed (optically isotropic) and uniaxiallystressed (optically anisotropic) nGaP in the quantum frequency regions has been carried out. At a pressure P = 10 ^{4} kgf cm ^{2}, parallel to the [100] direction, and at T = 300K, practically all the electrons previously uniformly distributed throughout all the equivalent valleys migrated into one lowered valley. This permitted the investigation of the components of the FCA coefficient at parallel (α _{∥}) and perpendicular (α _{⊥}) orientations of the field axis relative to the long axis of the mass tensor ellipsoid of the lowered valley. It is shown that the experimentallyobserved singularities of FCA in nGaP (varying frequency dependences α _{0}, α _{∥}, α _{⊥}, low value of the ratio {α _{⊥}}/{α _{∥}}^{(1)} and frequency dependence with the power less than {3}/{2}) can be explained within the framework of FCA quantum theory only if the intermediate states in the upper conduction band Δ _{2} and the intervalley scattering anisotropy are taken into account.
 Publication:

Infrared Physics
 Pub Date:
 September 1983
 DOI:
 10.1016/00200891(83)900775
 Bibcode:
 1983InfPh..23..277B
 Keywords:

 Anisotropic Media;
 Gallium Phosphides;
 Infrared Absorption;
 NType Semiconductors;
 Axial Stress;
 Crystal Optics;
 Impurities;
 SolidState Physics