Metalorganic chemical vapor deposition growth of InAs/GaSb type II superlattices with controllable As x Sb 1-x interface
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NANO EXPRESS
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Metalorganic chemical vapor deposition growth of InAs/GaSb type II superlattices with controllable AsxSb1-x interfaces Li-Gong Li1,2, Shu-Man Liu1*, Shuai Luo1, Tao Yang1, Li-Jun Wang1, Feng-Qi Liu1, Xiao-Ling Ye1, Bo Xu1 and Zhan-Guo Wang1
Abstract InAs/GaSb type II superlattices were grown on (100) GaSb substrates by metalorganic chemical vapor deposition (MOCVD). A plane of mixed As and Sb atoms connecting the InAs and GaSb layers was introduced to compensate the tensile strain created by the InAs layer in the SL. Characterizations of the samples by atomic force microscopy and high-resolution X-ray diffraction demonstrate flat surface morphology and good crystalline quality. The lattice mismatch of approximately 0.18% between the SL and GaSb substrate is small compared to the MOCVD-grown supperlattice samples reported to date in the literature. Considerable optical absorption in 2- to 8-μm infrared region has been realized. PACS: 78.67.Pt; 81.15.Gh; 63.22.Np; 81.05.Ea Introduction InAs/GaSb superlattices (SLs) are important for longwavelength infrared (IR) applications because of their broken gap type II band alignment with the conduction band minimum of InAs lying below the valence band maximum of GaSb. Such type II SL material has been investigated widely as a viable alternative to conventional HgCdTe IR detecting materials due to the unique capability for band structure engineering which results in great flexibility in controlling the detection wavelength (from 3 to 30 μm) [1], low Auger recombination rates [2,3] and small tunneling current [4]. Recently, quantum well IR photodetectors (QWIPs) [5-7] have also exhibited a number of potential advantages including highly uniform and well-controlled epitaxy growth, but their quatum efficiency cannot compete with HgCdTe photodiode due to the fact that optical transition is forbidden for normal incidence of light. More recently, new nanostructured IR photodectors based on quantum dots have been investigated intensively to outperform QWIPs since they are intrinsic sensitive to * Correspondence: [email protected] 1 Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, People’s Republic of China Full list of author information is available at the end of the article
normal incidence light [8-10]. However, the absorption efficiency is still low due to the limited density of dots and inhomogeneous dot size. In the case of InAs/GaSb SL structures, the absorption is strong for normal incidence of light. Consequently, the SL structures provide the possibility to have both high absorption efficiency as reached with HgCdTe and high uniform as reached with QWIPs. So far, high-quality InAs/GaSb materials have been grown by molecular beam epitaxy (MBE) [11-13]. However, the capability to grow device-quality material and structure by metalorganic chemical vapor deposition (MOCVD) has not been fully achieved, which is the preferred growth technique in manufacturing due to the higher
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