  Spectral properties of quarks above the critical temperature for
deconfinement are analyzed in quenched lattice QCD on lattices of size
128^3x16. We study quark spectral function in energy and momentum space,
focusing on the values of the thermal mass and the dispersion relations of
normal and plasmino modes at nonzero momentum, as well as their spatial volume
dependence. Our numerical result suggests that the dispersion relation of the
plasmino mode has a minimum at nonzero momentum even near the critical
temperature. The quark self-energy is also analyzed by using the analyticy of
the inverse propagator, which is found to be consistent with the spectral
function estimated by the two-pole ansatz.
