  We calculate nucleosynthesis in core-collapse explosions of massive Pop III
stars, and compare the results with abundances of metal-poor halo stars to
constrain the parameters of Pop III supernovae. We focus on iron-peak elements
and, in particular, we try to reproduce the large [Zn/Fe] observed in extremely
metal-poor stars. The interesting trends of the observed ratios [Zn, Co, Mn,
Cr, V/Fe] can be related to the variation of the relative mass of the complete
and incomplete Si-burning regions in supernova ejecta. We find that [Zn/Fe] is
larger for deeper mass-cuts, smaller neutron excess, and larger explosion
energies. The large [Zn/Fe] and [O/Fe] observed in the very metal-poor halo
stars suggest deep mixing of complete Si-burning material and a significant
amount of fall-back in Type II supernovae. Furthermore, large explosion
energies (E_51 >~ 2 for M ~ 13 Msun and E_51 >~ 20 for M >~ 20 Msun) are
required to reproduce [Zn/Fe] ~ 0.5. The observed trends of the abundance
ratios among the iron-peak elements are better explained with this high energy
(``Hypernova'') models rather than the simple ``deep'' mass-cut effect, because
the overabundance of Ni can be avoided in the hypernova models. We also present
the yields of pair-instability supernova explosions of M = 130 - 300 Msun
stars, and discuss that the abundance features of very metal-poor stars cannot
be explained by pair-instability supernovae.
