Long-wavelength room-temperature luminescence from InAs/GaAs quantum dots with an optimized GaAsSbN capping layer

Abstract

An extensive study on molecular beam epitaxy growth conditions of quaternary GaAsSbN as a capping layer (CL) for InAs/GaAs quantum dots (QD) was carried out. In particular, CL thickness, growth temperature, and growth rate were optimized. Problems related to the simultaneous presence of Sb and N, responsible for a significant degradation of photoluminescence (PL), are thereby solved allowing the achievement of room-temperature (RT) emission. A particularly strong improvement on the PL is obtained when the growth rate of the CL is increased. This is likely due to an improvement in the structural quality of the quaternary alloy that resulted from reduced strain and composition inhomogeneities. Nevertheless, a significant reduction of Sb and N incorporation was found when the growth rate was increased. Indeed, the incorporation of N is intrinsically limited to a maximum value of approximately 1.6% when the growth rate is at 2.0 ML s−1. Therefore, achieving RT emission and extending it somewhat beyond 1.3 μm were possible by means of a compromise among the growth conditions. This opens the possibility of exploiting the versatility on band structure engineering offered by this QD-CL structure in devices working at RT.PACS81.15.Hi (molecular beam epitaxy); 78.55.Cr (III-V semiconductors); 73.21.La (quantum dots)

Sb and N Incorporation Interplay in GaAsSbN/GaAs Epilayers near Lattice-Matching Condition for 1.0–1.16-eV Photonic Applications

“…Quaternary samples C1, C2 and C3 were grown at 470 °C with a fixed N flux and different Sb fluxes (see Table 1). A high growth rate of 2 ML/s is chosen in these N- and Sb-containing structures since it has been shown to strongly improve the PL emission in other samples containing the quaternary alloy [29]. A GaAsN sample (C0) was grown as a reference.…”

“…This research focuses on the growth control of high-quality GaAsSbN layers grown at 2 ML/s for photonic devices in the bandgap range of 1–1.16 eV. The use of growth rates higher than the one commonly applied in GaAs-based compounds (~1 ML/s) has been proved to have a positive impact in other N-containing structures, probably by reducing the composition modulation as a result of a lower diffusion of N and Sb atoms on the growth surface [29]. Moreover, we have taken advantage of the radial composition drift of the MBE growth, induced by the substrate temperature gradient, to multiply the range of the compositions of Sb and N obtained in each growth.…”

Calculation of Elastic Bond Constants in Atomistic Strain Analysis

“…Accordingly, the energy band structures of the tailored structures can thus be modified. When shedding light on device designing, in particular, the strain-engineered formation of heterostructures, junctions, and variable composition profiles in quantum dots (QDs) and nanowires (NWs) during epitaxial growth [ 8 , 9 ], strain provides a key strategy for producing optimal nanophotonic and nanoelectronic materials, including high-efficiency blue and green light-emitting diodes (LEDs) [ 10 , 11 ], visible lasers [ 12 – 14 ], and high-efficiency solar cells [ 15 ]. Moreover, studies on the strain effect incorporated in two-dimensional (2D) materials [ 16 – 18 ] and topological insulators [ 19 – 21 ] also open doors to new classes of electronic and spintronic devices.…”

Tuning the properties of InAs/GaAs quantum dots through a modified capping layer: Application to optoelectronic devices

“…The initial comparative analysis was carried out using 5 nm-thick GaAsSbN and GaAsN CLs (samples S-SbN and S-N, respectively). A 2MLs -1 growth rate, particularly beneficial for N-containing samples [252], as shown in Chapter 7, was used for the growth of the CL in all these samples. The Sb and N nominal contents were always set to 10 and 2.0%, respectively.…”

“…In an effort to obtain improved characteristics using the quaternary CL, alternative structures containing simultaneously Sb and N were designed. The other two successful growth approaches for the quaternary CL shown in Chapter 7 were used, namely, a thin CL [252] and a superlattice-like CL [183]. Two new samples were fabricated following the same procedure described in Section 8.2.…”