Strong emission from As monolayers in AlSb

Strong photoluminescence (PL) bands between 1.41 and 1.62 eV have been obse rved from superlattices (SL's) composed of fractional or single monolayers (ML) of AlAs separated by 22-49 ML of AlSb. The emission exhibits a weak de pendence on the SL period but shifts significantly to higher energy with de creasing AlAs thickness. Optically detected magnetic-resonance (ODMR) exper iments at 24 GHz on the 1.45-eV PL from the SL's with similar to 1 ML of Al As reveal S = 1/2 electron spin transitions with g(parallel to) = (1.916- 1 .923) +/- 0.002 and g(perpendicular to) = (1.934- 1.944) +/- 0.002 split by an exchange interaction (Delta) of (3.4-8.0) +/- 0.2 mu eV with holes deri ved from the J(z)= +/- 3/2 valence band. Exchange-split electron resonances with g(parallel to) = 1.868+/-0.002 and g(perpendicular to) = 1.882 +/- 0. 002 and Delta = 19.5+/-0.5 mu eV were detected on the 1.62-eV band from a s ample with 31 ML of AlSb and 0.27 ML of AlAs. The PL and ODMR results can b e understood using a type-II band lineup with the electron localized at the AlAs ML and the hole excluded to the AlSb layers. The electron g values an d the strength of the exchange interaction reflect the degree of wave-funct ion penetration into the adjacent AlSb barriers. The weakly bound excitons are localized at fluctuations along the AlSb/AlAs interfaces. [S0163-1829(9 9)00303-3].