  To clarify the whole picture of the valence-band structures of prototype
ferromagnetic semiconductors (III,Mn)As (III: In and Ga), we perform systematic
experiments of the resonant tunneling spectroscopy on [(In_0.53Ga_0.47)_1-x
Mn_x]As (x=0.06-0.15) and In_0.87Mn_0.13As grown on AlAs/ In_0.53Ga_0.47As:Be/
p+InP(001). We show that the valence band of InGaMnAs almost remains unchanged
from that of the host semiconductor InGaAs, that the Fermi level exists in the
band gap, and that the p-d exchange splitting in the valence band is negligibly
small in (InGaMn)As. In the In0.87Mn0.13As sample, although the resonant peaks
are very weak due to the large strain induced by the lattice mismatch between
InP and InMnAs, our results also indicate that the Fermi level exists in the
band gap and that the p-d exchange splitting in the valence band is negligibly
small. These results are quite similar to those of GaMnAs obtained by the same
method, meaning that there are no holes in the valence band, and that the
impurity-band holes dominate the transport and magnetism both in the InGaMnAs
and In_0.87Mn_0.13As films. This band picture of (III,Mn)As is remarkably
different from that of II-VI-based diluted magnetic semiconductors.
