  The thermal power ($PF=S^2G_e$) depends on the Seebeck coefficient ($S$) and
electron conductance ($G_e$). The enhancement of $G_e$ will unavoidably
suppress $S$ because they are closely related. As a consequence, the
optimization of $PF$ is extremely difficult. Here, we theoretically
investigated the thermoelectric properties of two-dimensional quantum dot (QD)
arrays with carriers injected from electrodes. The Lorenz number of 2D QD
arrays in the resonant tunneling procedure satisfies the Wiedemann-Franz law,
which confirms the formation of minibands. When the miniband center is far away
from the Fermi level of the electrodes, the electron transport is in the
thermionic-assisted tunneling procedure (TATP). In this regime, $G_e$ in
band-like situation and $S$ in atom-like situation can happen simultaneously.
We have demonstrated that the enhancement of $G_e$ with an increasing number of
electronic states will not suppress $S$ in the TATP.
