In this paper we deal with a mathematical model for the description of heat
conduction and carrier transport in semiconductor heterostructures. We sol
ve a coupled system of nonlinear elliptic differential equations consisting
of the heat equation with Joule heating as a source, the Poisson equation
for the electric field and drift-diffusion equations with temperature depen
dent coefficients describing the charge and current conservation; subject t
o general thermal and electrical boundary conditions. We prove the existenc
e and uniqueness of Holder continuous weak solutions near thermodynamic equ
ilibria points using the Implicit Function Theorem. To show the continuous
differentiability of maps corresponding to the weak formulation of the prob
lem we use regularity results from the theory of nonsmooth linear elliptic
boundary value problems in Sobolev-Campanato spaces.