Anisotropy of thermal conductivity and energy-flux relaxation time of hot electrons in semiconductors

In this article a theoretical and computational analysis of the hot-electron thermal conductivity and related quantities in semiconductors is given. Two types of anisotropy are analyzed: the first is related to the dependence of the thermal conductivity on the direction of an externally applied electric field; the second is associated to the difference between the longitudinal and transverse thermal conductivity (i.e., along the field direction and along a direction perpendicular to the field, respectively). Two theoretical approaches based on a set of generalized relaxation times or on a set of microscopic correlation functions are considered and compared. Numerical results are obtained using a Monte Carlo simulator for electrons in silicon at 77 and 300 K. This approach can be extended to other semiconductors of interest within a semiclassical approach where two-particle interactions are neglected. (C) 1999 American Institute of Physics. [S0021-8979(99)06502-0].