  The tunneling density of states of HTSC is calculated taking into account
tight binding band structure, group velocity, and tunneling directionality for
s-wave and d-wave gap symmetry. The characteristic density of states has
quasiparticle peaks' asymmetry, flat s-wave and cusplike d-wave case subgap
behavior, and asymmetric background. We consider that the underlying asymmetry
of the conductance peaks is primarily due to the features of quasiparticle
energy spectrum, and the d-wave symmetry enhances the degree of the peaks'
asymmetry. Increasing of the lifetime broadening factor changes the degree of
tunneling conductance peaks' asymmetry, and leads to the confluence of the
quasiparticle and van Hove singularity peaks.
