Shape Control and Emission-wavelength Extension of InP-based InAsSb Nanostructures
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1208-O04-02
Shape control and emission wavelength extension of InP-based InAsSb nanostructures Wen Lei, H.H. Tan, and C. Jagadish Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200, Australia
Abstract This paper presents a study on the shape control and emission wavelength extension of InPbased InAsSb nanostructures. InGaAs buffer layer, combined with low growth temperature and medium V/III ratio, provides an effective approach to fabricate InAsSb QDs. By using InGaAsSb sandwich layer to serve as both strain reducing layer and metamorphic buffer layer, the emission wavelength of InAsSb QDs can be extended well beyond 2 µm, which is very useful for their application as mid-infrared emitters. Introduction InP-based InAsSb quantum dots (QDs) have attracted much attention due to their potential application as mid-infrared emitters, which have a wide range of applications in military, telecommunications, molecular spectroscopy, biomedical surgery, environmental protection and manufacturing industry.[1-3] Some work has been done on the direct growth of InAsSb nanostructures on InP substrates, and flat InAsSb quantum dashes (QDashes) are obtained due to the surfactant effect of Sb atoms.[4-6] In the meantime, though the theoretical study indicated that the emission wavelength of InAsSb nanostructures can be extended above 2 µm, even reaching 5µm,[1] InAsSb nanostructures formed by direct growth only shows an emission wavelength around 1.8 µm due to their small island height and the high compressive strain in nanostructures. To achieve their application as mid-infrared emitters, the emission wavelength of InAsSb QDs should be extended beyond 2 µm. In this paper, we present a study on the shape control and emission wavelength extension of InP-based InAsSb nanostructures. By using InGaAs buffer layer and appropriate growth conditions, circular InAsSb QDs are obtained with high density. The emission wavelength of InAsSb QDs is extended to ~ 2.3 µm by using InGaAsSb sandwich layers as strain reducing layers. Experimental details The samples were grown on semi-insulating InP (001) substrates in a horizontal flow MetalOrganic Chemical Vapour Deposition reactor (Aixtron, AIX 200/4) at a pressure of 180 mbar. Trimethylindium (TMIn), trimethylgallium (TMGa), trimethylaluminum (TMAl), trimethylantimony (TMSb), PH3, and AsH3 were used as precursors and ultra-high purity H2 as the carrier gas. To study the effect of buffer layer on the shape of the nanostructure, InAsSb nanostructures were deposited on three kinds of buffer layers: In0.53Ga0.47As, InP, and
In0.52Al0.48As. The InAsSb/In0.53Ga0.47As nanostructure sample was grown with the following layer sequence: first, a 100 nm InP layer was deposited at 650 °C followed by a 100 nm InGaAs layer also at 650 °C. Growth was then interrupted and the temperature dropped to a certain growth temperature Tg to grow 4 monolayer (ML) of InAs0.5Sb0.5. The InAsSb were immediately capped with 5 nm In
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