Optical and transport measurements, carried out on pn diodes and Schottky barriers containing multi-layers of InAlAs quantum dots embedded in AlGaAs barriers, showed that whereas a red emission from quantum-dot states was obtained at ~1.8eV, defect states dominated the optical properties and transport in these dots. These defects provided non-radiative recombination paths which shortened the carrier lifetimes in quantum-dots to tens of picoseconds, from ~1ns, and produced deep-level transient spectroscopy peaks in both p- and n-type structures. Deep-level transient spectroscopy, performed using short filling pulses and bias-dependent measurements, of InAlAs quantum-dots on n-AlGaAs barriers showed that one of the peaks could be attributed to either quantum-dot/barrier interfacial defects or to quantum-dot electron levels. Other peaks were attributed to defect states in both p- and n-type structures.

Defect States in Red-Emitting InxAl1–xAs Quantum Dots. R.Leon, J.Ibáñez, S.Marcinkevičius, J.Siegert, T.Paskova, B.Monemar, S.Chaparro, C.Navarro, S.R.Johnson, Y.H.Zhang: Physical Review B, 2002, 66[8], 085331 (7pp)