Deep levels in uniformly Si doped GaAs/AlxGa1−xAs quantum wells and superlattices

Abstract

Uniformly Si doped GaAs/Al0.33Ga0.67As multilayer structures have been studied by deep level transient spectroscopy (DLTS) and photocapacitance measurements. DLTS spectra showed five peaks which are related to defects in the GaAs layers. The concentration of these defects decreased with increasing layer thickness. An additional peak, which has been observed with forward bias filling pulses, is suggested to be related to defects near the surface, most probably due to defect accumulation in multilayers. Their emission and capture properties as well as photoionization cross sections have been studied. Evidence is provided that the emission and filling processes of these deep levels are modified due to the energy quantization in the conduction band and the carrier transport through the quantum structures. No DX center related DLTS peaks or other features like persistent photoconductivity effects have been observed in any of our samples.

Defect states in red-emittingInxAl1−xAsquantum dots

“…7 for the peak found at short filling pulses in the n-InAlAs samples, and to the sharply increasing signal attributed to interfacial defects in other reports that include AlGaAs based superlattices. 25 Hole traps in AlGaAs devices have been reported in n-type AlGaAs/InGaAs PHEMT's which were attributed to surface states at ungated AlGaAs regions, but their reported activation energies were much higher than the E a ϭ0.37 eV measured in this work. 26 DLTS analysis in the InAlAs/n-AlGaAs structures presents an even more complex picture.…”

“…As was reported in earlier studies, 11,12,29 interfacial defects have been known to give strong DLTS signals and are also known to hamper radiative recombination from QD states. Interfacial defects have been observed 25,26 to have a rapid increase in signal intensity with applied bias as the bias sweeps over the interfacial region. An unambiguous identification of the origin of this broad low-temperature peak that is seen mainly for short filling pulses in InAlAs/n-AlGaAs QD's can only be made if the defect concentration can be reduced to a much lower density that the QD volumetric density, which will require additional growth optimization in future work.…”

Deep-level Transient Spectroscopy of GaAs/AlGaAs Multi-Quantum Wells Grown on (100) and (311)B GaAs Substrates

“…Using DLTS technique, Jia et al . [4] investigated Si-doped GaAs/AlGaAs quantum wells and superlattices and demonstrated that the energy of the well-known DX centre in AlGaAs epilayers decreases in the case of multi-quantum wells and increases for superlattices. Arbaoui et al .…”