Comparison of InAs quantum dots grown on GaInAsP and InP

Abstract

We report on the growth of InAs quantum dots (QDs) on GaInAsP and InP buffers by metal-organic chemical vapour deposition on InP(100) substrates. Indium segregation and the AsP exchange reaction affect the QD nucleation and composition. The AsP exchange reaction has a more pronounced effect on the QDs grown on the InP buffer than on those grown on the GaInAsP buffer. A very thin (0.6 nm) GaAs interlayer grown between the buffer layer and the InAs QD layer consumes segregated indium and minimizes the As/P exchange reaction. Wavelength tuning from 1450 to 1750 nm covering the technologically important 1550 nm wavelength is also achieved for the InAs QDs grown with the thin GaAs interlayer.

InAs nanostructures on InP (001) substrate with the insertion of a superthin AlAs layer

“…During the MBE growth of a 2-or 3-ML AlAs layer on the buffer, RHEED patterns along the [1][2][3][4][5][6][7][8][9][10] azimuth was streaky, which shows that the tensile-strained AlAs layer can be grown in two-dimension up to 3 ML. Figure 2(a) is the 5 × 5 µm 2 AFM image of sample F with a 3-ML AlAs layer beneath, and there are a large irregular pit with the number density of ~2 × 10 8 cm 2 on the surface.…”

“…Therefore, the (InAs) x (AlAs) 1−x nanostructure resulting from the spinodal decomposition in the InAlAs alloy is more significant than the corresponding (InAs) x (GaAs) 1−x one in the InGaAs alloy. The nanostructure in the InAlAs or InGaAs alloy is generally anisotropic along the [1][2][3][4][5][6][7][8][9][10] and [110] directions [27][28][29], and it may be the mechanism for the formation of InAs wires on the InP substrate [4]. It seems that such a mechanism can be effectively suppressed by the insertion of an ultrathin AlAs layer on the InGaAs buffer, while it still plays an important role in the self-assembling of InAs wires on the InAlAs buffer on the InP substrate.…”

“…The fabrication of InAs/GaAs QDs has achieved much progress in recent years. In comparison, the controlling of the emission wavelength from the InAs/InP QDs still remains a great challenge due to some complications and difficulties in the epitaxial growth of InAs/InP using molecular-beam epitaxy (MBE), metal-organic chemical vapor deposition (MOCVD), or chemical-beam epitaxy (CBE) [1,2]. The lattice mismatch between InAs and InP is 3.2 %, relatively small in comparison with 7 % in the InAs/GaAs system, and InGa(Al)As or InGaAsP alloy buffers may undergo spinodal decomposition [3,4], resulting in the modification of the surface nano-morphology [5].…”

Shorter wavelength emission with InAs quantum dots growth directly on large bandgap quaternary (In0.68Ga0.32As0.7P0.3) barriers for high current injection efficiency

“…Very low threshold semiconductor lasers, such as quantum dot lasers, are naturally good candidates for these applications. High-quality self-assembled QD lasers based on InAs/GaAs [1][2][3] and InAs/InP [4][5][6][7][8] have been demonstrated. InAs QDs on InP substrates have been shown to emit in the wavelength range of 1200-2000 nm with high efficiency [9][10][11].…”

“…The problem with this is the difficulty of obtaining emission in the wavelength range required for telecom ($ 1550 nm). The literature reports on InAs/InGaAsP QD layers that are tuned for 1550 nm emission by the insertion of ultrathin GaAs interlayers [4,12,13]. The major problem with this approach is the insertion of an additional potential barrier for carrier injection.…”