Investigation of radiative and nonradiative trap centers in ZnSe:Al layers grown by molecular beam epitaxy

Abstract

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 2×1018 cm−3, the other set includes heavily doped ZnSe:Al layers whose net-doping density is 1×1017 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.

Photoluminescence and surface photovoltage properties of ZnSe nanoribbons

“…The DD states are usually treated as the recombination centers, which has been widely studied with PL techniques, including the PL of ZnSe which grows under Zn-and Se-rich atmosphere, temperature-dependent, time-and spatial-resolved PL [15][16][17][18][19]. However, little attention has focused on the trap effect of the DD states correlating with photoelectric response understood as separation of photogenerated carriers, which competes with the radiative pathway for PL emission [20]. Surface photovoltage (SPV), generated from the special separation of photogenerated electron-hole pairs, has been applied in nondestructive characterization of the optoelectronic properties for bulk and nanostructured semiconductor materials [21][22][23][24].…”