Characteristics of Strained GaAsSb(N)/InP Quantum Wells Grown by Metalorganic Chemical Vapor Deposition on InP Substrate
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Characteristics of Strained GaAsSb(N)/InP Quantum Wells Grown by Metalorganic Chemical Vapor Deposition on InP Substrates Dapeng Xu1, Juno Yu-Ting Huang1, Joo Hyung Park1, Luke J. Mawst1, Thomas F. Kuech2, XUEYAN SONG3, and Susan E. Babcock3 1 Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, WI, 53706 2 Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI, 53706 3 Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, 53706 ABSTRACT GaAsSb (N) superattices (SLs) grown on InP substrates using metalorganic vapor phase epitaxy are investigated by high-resolution x-ray diffraction (XRD), low-temperature photoluminescence (PL), and high-resolution transmission electron microscopy (TEM). XRD shows very sharp satellite peaks and pendellosung fringes, which indicates excellent crystalline quality and abrupt interfaces in the GaAsSb (N)/InP SL, with Sb varies with 0.2 to 0.7. Low temperature PL shows clearly different features between the 25% Sb and 44% Sb samples. A band alignment difference is proposed to explain these behaviors. Experimental data establishes that the transition from a type-I to a type-II heterostructure occurs for a Sb-content of approximately 40%, which agrees well with the prediction by Model Solid Theory. While N incorporation degrades the PL intensity, it also provides the greater electron confinement needed to achieve mid-IR emission from GaAsSbN/GaAsSb type-II QWs
INTRODUCTION The novel III-V GaAsSb (N) alloy is a potentially important material for InP-based microelectronics and optoelectronics devices. GaAsSb/InP heterostructures can exhibit type-II band alignment, which provides a solution to the current back injection problem common in heterojunction bipolar transistor designs based on InGaAs/InP[1-2]. InGaAs/GaAsSb type-II ìWî QW structures on InP substrate have also been realized by Peter et al. employing a superlattice active region consisting of compressively-strained InGaAs and tensile-strained GaAsSb[3]. Another potential application is InP-based GaAsSbN/GaAsSb type-II QW structures for achieving emission in the 2-3 µm wavelength regions [4]. Due to the difficulties of growing high-quality GaAsSb/InP QWs, there are few studies existing on the optical properties of highly strained GaAsSb QWs on InP substrates, as most previous work has involved bulk material [5]. Strained QWs in this material system spanning the composition range from GaAs to GaSb have not been reported. Band offsets, the Sb content resulting in a transition from a type-I to a type-II QW, and luminescent properties have not been established for strained QWs on InP. We have undertaken a comprehensive study of the characteristics of strained GaAsSb QWs on InP substrates. Optical and structural quality of this important material system is determined from variable temperature photoluminescence, SIMS, xray diffraction, and TEM of thin SL structures
The addition of nitrogen into GaAsSb further reduces the bandgap energy to access l
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