Abstract
We have investigated the structural and optical properties of type-II GaSb/InGaAs quantum dots [QDs] grown on InP (100) substrate by molecular beam epitaxy. Rectangular-shaped GaSb QDs were well developed and no nanodash-like structures which could be easily found in the InAs/InP QD system were formed. Low-temperature photoluminescence spectra show there are two peaks centered at 0.75eV and 0.76ev. The low-energy peak blueshifted with increasing excitation power is identified as the indirect transition from the InGaAs conduction band to the GaSb hole level (type-II), and the high-energy peak is identified as the direct transition (type-I) of GaSb QDs. This material system shows a promising application on quantum-dot infrared detectors and quantum-dot field-effect transistor.
Highlights
Quantum-size nanostructure materials have always been the research focus [1,2,3,4,5]
The results indicate that the rectangular-shaped GaSb/InGaAs QDs are well developed in the SK growth mode, but no nanodash-like structures which are found in the InAs/InP QD system were formed [19]
We did not observe such bimodal distribution in the STEM images. We thought that these mound-like structures were possibly from the non-optimized InGaAs buffer layer. Another possible explanation was that the formation of the InGaAsSb wetting layer resulted in the accumulation of individual atoms on the surface to form a mound-like structure, due to the intermixing of As and Sb during the growth of GaSb QD
Summary
Quantum-size nanostructure materials have always been the research focus [1,2,3,4,5]. The reason is that they offer comparatively large bandgap energies and provide a possibility of covering the whole middle and far-infared optical range for photoelectric devices Among these material systems, GaSb/GaAs quantum dot [QD] is an outstanding representative since its giant valence band offset, characteristic to this system, may result in practical applications for light-emitting devices in the spectral range of 1 to approximately 1.5 μm, such as in ophthalmology, neurology, and endoscopy [18]. GaSb/GaAs quantum dot [QD] is an outstanding representative since its giant valence band offset, characteristic to this system, may result in practical applications for light-emitting devices in the spectral range of 1 to approximately 1.5 μm, such as in ophthalmology, neurology, and endoscopy [18] We provided another type-II QD material system, GaSb/InGaAs/InP, as another promising building block for optoelectronic and microelectronic applications. All these features show a promising application on the quantum-dot infrared detectors [QDIP] and quantum-dot field-effect transistors [QD-FET]
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