  The Monte Carlo technique is used to calculate electrical as well as
thermoelectric transport properties across thin film heterostructures. We study
a thin InGaAsP barrier layer sandwiched between two InGaAs contact layers, when
the barrier thickness is in 50nm-2000nm range. We found that with decreasing
size, the effective Seebeck coefficient is increased substantially. The
transition between pure ballistic thermionic transport and fully diffusive
thermoelectric transport is also described.
