Carrier delocalization in InAs/InGaAlAs/InP quantum-dash-based tunnel injection system for 1.55 µm emission

Abstract

We have investigated optical properties of hybrid two-dimensional-zero-dimensional (2D-0D) tunnel structures containing strongly elongated InAs/InP(001) quantum dots (called quantum dashes), emitting at 1.55 μm. These quantum dashes (QDashes) are separated by a 2.3 nm-width barrier from an InGaAs quantum well (QW), lattice matched to InP. We have tailored quantum-mechanical coupling between the states confined in QDashes and a QW by changing the QW thickness. By combining modulation spectroscopy and photoluminescence excitation, we have determined the energies of all relevant optical transitions in the system and proven the carrier transfer from the QW to the QDashes, which is the fundamental requirement for the tunnel injection scheme. A transformation between 0D and mixed-type 2D-0D character of an electron and a hole confinement in the ground state of the hybrid system have been probed by time-resolved photoluminescence that revealed considerable changes in PL decay time with the QW width changes. The experimental discoveries have been explained by band structure calculations in the framework of the eight-band k⋅p model showing that they are driven by delocalization of the lowest energy hole state. The hole delocalization process from the 0D QDash confinement is unfavorable for optical devices based on such tunnel injection structures.

1.5 μm quantum-dot diode lasers directly grown on CMOS-standard (001) silicon

“…are separated from an InGaAs QW by the ultrathin InAlGaAs barrier for more efficient carrier injection29 . Also, increasing the Indium composition in the InGaAs interlayers to introduce a larger strain field would be beneficial for enhanced dislocation filtering.…”

InAs/InP quantum-dash lasers

“…Very recently, Rudno-Rudzi nski et al [41] investigated the influence of the width of the quantum well layer on the injection-tunneling of Qdash based material system. The InAs Qdashes were separated from the InGaAs quantum-well layer by a 2.3-nm thick barrier layer.…”

Carrier dynamics in hybrid nanostructure with electronic coupling from an InGaAs quantum well to InAs quantum dots

“…A second approach is to architect the "injection-structure" by separating the QD layer from the QW with a thin barrier. This approach is particularly interesting because it allows for more independent control of the QDs, as well as the ability to inject carriers from the QW to the QDs [19][20][21][22]. The nanostructures obtained via this second approach have been explored most recently to improve the device performance for lasers and photovoltaics [22,23].…”