  Recently new quantum features were observed and studied in the ridged quantum
wells (RQW). Periodic ridges on the surface of the quantum well layer impose
additional boundary conditions on electron wave function and reduce quantum
state density. As result, chemical potential of RQW increases and becomes the
ridge height dependent. Here we propose system comprising of RQW and additional
layer on the top of the ridges forming periodic series of p+-n+ junctions (or
metal-n+ junctions). In such systems charge depletion region develops inside
the ridges and effective ridge height reduces, becoming rather strong function
of temperature T. Consequently, T dependence of chemical potential magnifies
and Seebeck coefficient S increases. We investigate S in the system of
semiconductor RQW having abrupt p+-n+ junctions or metal-n+ junctions on the
top of the ridges. Analysis made on the basis of Boltzmann transport equations
shows dramatic increase in S for both cases. At the same time other transport
coefficients remain unaffected by the junctions. Calculations show one order of
magnitude increase in thermoelectric figure of merit ZT relative to the bulk
material.
