Measurement of InAsSb bandgap energy and InAs/InAsSb band edge positions using spectroscopic ellipsometry and photoluminescence spectroscopy

Abstract

"Measurement of InAsSb bandgap energy and InAs/InAsSb band edge positions using spectroscopic ellipsometry and photoluminescence spectroscopy" (2015). The structural and optical properties of lattice-matched InAs 0.911 Sb 0.089 bulk layers and strainbalanced InAs/InAs 1Àx Sb x (x $ 0.1-0.4) superlattices grown on (100)-oriented GaSb substrates by molecular beam epitaxy are examined using X-ray diffraction, spectroscopic ellipsometry, and temperature dependent photoluminescence spectroscopy. The photoluminescence and ellipsometry measurements determine the ground state bandgap energy and the X-ray diffraction measurements determine the layer thickness and mole fraction of the structures studied. Detailed modeling of the X-ray diffraction data is employed to quantify unintentional incorporation of approximately 1% Sb into the InAs layers of the superlattices. A Kronig-Penney model of the superlattice miniband structure is used to analyze the valence band offset between InAs and InAsSb, and hence the InAsSb band edge positions at each mole fraction. The resulting composition dependence of the bandgap energy and band edge positions of InAsSb are described using the bandgap bowing model; the respective low and room temperature bowing parameters for bulk InAsSb are 938 and 750 meV for the bandgap, 558 and 383 meV for the conduction band, and À380 and À367 meV for the valence band. V C 2015 AIP Publishing LLC.[http://dx

Optical properties of InAsBi and optimal designs of lattice-matched and strain-balanced III-V semiconductor superlattices

“…The bandgap bowing parameter of InAsSb is 938 meV at low temperature and 750 meV at room temperature, and the valence band bowing parameter of InAsSb is À380 meV at low temperature and À367 meV at room temperature. 20 The bandgap bowing parameter of GaInSb is 413 meV at low temperature and 398 meV at room temperature. 21 The valence band bowing parameter of GaInSb is zero implying that the bandgap bowing occurs entirely in the conduction band of GaInSb; no temperature dependence has been reported.…”

“…The unintentional Sb in the InAs layers of the superlattice is not quantifiable due to the short period thickness of this sample; therefore, an unintentional Sb mole fraction of 0.024 is assumed based on the unintentional Sb measured in other InAs/InAsSb superlattices grown under the similar conditions. 20 The sample cross section is shown in the inset of Fig. 15.…”

“…In the analyses, the bandgap absorption coefficient and energy are determined using the first derivative maximum method. 20 The low temperature bandgap energies are obtained from the literature for the binary materials 2 and InAs 0.911 Sb 0.089 , 20 and from this work for InAs 0.932 Bi 0.064 .…”

“…A Nicolet Instrument Corporation Magna-IR 760 Fourier transform infrared spectrometer is used to measure room temperature photoluminescence from the 1.0 lm thick optimal InAs/InAsSb superlattice grown at 425 C as well as a 0.5 lm thick bulk lattice-matched InAs 0.911 Sb 0.089 sample grown at 430 C. 20 The samples are excited using an 808 nm pump laser and 200 mW of laser power. Fig.…”

“…The room temperature absorption coefficient of bulk InAs 0.911 Sb 0.089 has been measured as a function of photon energy using spectroscopic ellipsometry; 20 the first derivative maximum of the absorption coefficient identifies the bandgap absorption coefficient a g as 2240 cm…”