  Thermoelectric power due to coherent electron transmission through a quantum
dot is theoretically studied. In addition to the known features related to
resonant peaks, we show that a novel significant structure appears between the
peaks. This structure arises from the so-called transmission zero, which is
characteristic of coherent transmission through several quantum levels. Because
of sensitivity to phase-breaking effect in quantum dots, this novel structure
indicates degree of coherency in the electron transmission.
