GENERALIZATION OF THERMAL-CONDUCTIVITY AND LORENZ NUMBER TO HOT-CARRIER CONDITIONS IN NONDEGENERATE SEMICONDUCTORS

We present a generalization to high-field transport of the carrier the rmal conductivity and Lorenz number in nondegenerate semiconductors. T he theory is based on the correlation-function formalism. In its range of validity, it provides exact values and predicts an anisotropic beh avior of the above parameters with respect to the direction of the app lied field. Calculations for the case of n-Si at 300 K evidence a dram atic decrease, more than 2 orders of magnitude, of the longitudinal va lues at the highest fields of 100 kV/cm.