A theoretical investigation has been made of the collective (bulk and
surface) excitations in a semiinfinite n-i-p-i superlattice system in
the presence of a magnetic field oriented perpendicular to the interfa
ces and to the direction of propagation. The thicknesses of the consti
tuent layers is assumed to be sufficiently large so that the quantum-w
ell effects can be ignored. The material layers are characterized by f
requency- and magnetic-field-dependent dielectric functions. The magne
toplasma modes are defined by electromagnetic fields that are localize
d at and decay exponentially away from the interfaces and from the end
of the superstructure. The general dispersion relations are derived u
sing a fully retarded theory in the framework of a transfer-matrix met
hod. Numerical examples are presented for several illustrative cases.