ABSTRACT
InGaAs/AlAsSb multiple-quantum wells (MQWs) lattice matched to InP substrate have been grown by molecular beam epitaxy. By precisely controlling the As to Sb flux ratio and substrate temperature, fairly abrupt interfaces with 1~2 monolayers of compositionary varying layers in both heterointerfaces confirmed from high-resolution transmission electron microscopy (HRTEM) lattice images have been achieved. We have observed intersubband transitions (ISBTs) at 1.23 pm (1.01 eV) and 1.45 μm (0.82 eV) from a InGaAs/AlAsSb coupeld doublequantum well (C-DQW) structure with 2.1 nm InGaAs wells and 2 nm center barrier layer. This is the first observation of the intersubband absorption in CDQWs that exibit two different transition wavelengths shorter than 1.5 pm ever reported in any materials system.
