Radiative and nonradiative trap centers for two typical sets of ZnSe:Al layers in a carrier compensation region, grown by molecular beam epitaxy, were investigated in terms of photoluminescence (PL) and photocapacitance (PHCAP) measurements. One set includes lightly doped ZnSe:Al layers whose net-doping density is 2 x 10(18) cm(-3), the other set includes heavily doped ZnSe:Al layers whose net-doping density is 1 x 10(17) cm(-3) due to carrier compensation. In 10 K PL spectra, the lightly doped ZnSe:Al layer shows dominant donor-bound exciton emission, while the heavily doped ZnSe:Al layer shows strong deep-level emission via radiative trap centers at 1.97 eV (RD1) and 2.23 eV (RD2). Moreover, the heavily doped ZnSe:Al layer shows another nonradiative electron trap center at 2.35 eV (ND3) in 100 K PHCAP spectra. Consequently, it is suggested the two radiative trap centers (RD1 and RD2) and one nonradiative trap center (ND3) contribute to carrier compensation in ZnSe:Al layers. (C) 2004 American Vacuum Society.