Abstract Body: III-V-bismide alloys have received significant attention over the past few decades due to the extreme bandgap reduction induced by the introduction of small concentrations of bismuth. However, dilute-bismides have struggled to achieve material quality commensurate with other III-V alloys, often attributed to the dramatically different growth temperatures of III-Bi and III-Sb/As materials. InSb1-xBix is a particularly promising candidate for accessing the midwave- to longwave-infrared (MWIR, LWIR respectively) with high-performance optical devices. Surprisingly, while GaSb1-xBix and InAs1-xBix have been widely studied, InSb1-xBix remains comparatively underexplored, with relatively few experimental investigations since the alloy was first synthesized nearly 50 years ago.1 In particular, growth in the “unity sticking” regime2 has not been demonstrated and photoluminescence (PL) has not been observed. In this work, we demonstrate high-quality InSb1-xBix films that exhibit a linear dependence of the bismuth concentration on the bismuth flux and, consequently, report the first PL from InSb1-xBix alloys. Epitaxial films, nominally 250 nm thick, were grown by solid-source molecular beam epitaxy on n-type (100) InSb substrates using a growth regime similar to that employed for high-quality GaSb1-xBix3 and InAs1-xBix4 synthesis. Samples were grown at a low substrate temperature of approximately 300°C with V/III flux ratios near stoichiometry. A comparatively fast growth rate of approximately 1 µm/hr was utilized to encourage bismuth incorporation. X-ray diffraction (XRD), PL, and atomic force microscopy (AFM) measurements were performed to characterize the bismuth content, optical quality, and surface roughness. X-ray diffraction measurements of the InSb1-xBix films suggested bismuth concentrations up to ~1.8%, assuming a lattice constant of 6.63 Å for InBi, which is reasonable given Rutherford backscattering spectrometry (RBS) measurements of both InAs1-xBix5 and InSb1-xBix.6 Photoluminescence measurements of the same InSb1-xBix films showed a red shift of PL associated with the InSbBi with increasing bismuth concentration. Specifically, PL measurements suggest a bandgap reduction of ~23 meV/% bismuth, which is comparable to previous reports of bandgap reduction estimated from optical absorption measurements of InSb1-xBix films.1,6 Temperature-dependent PL measurements of the highest Bi concentration film, containing 1.8% bismuth, showed a decrease in bandgap energy with increasing temperature that is consistent with a direct interband transition. AFM measurements of all films showed relatively smooth surfaces (RMS roughness of approximately 1 nm), however the highest concentration film exhibited large bismuth droplets. We expect droplet formation could be mitigated through optimization of the growth parameters. Thorough studies of the full growth space, particularly substrate temperature, as well as the effects of annealing on optical properties are in progress and will be presented. This work was supported by Lockheed Martin and NSF (ECCS-1933836). This work was performed in part at the University of Texas Microelectronics Research Center, a member of the National Nanotechnology Coordinated Infrastructure (NNCI), which is supported by the NSF (No. ECCS-1542159). This work was also supported by an NSF Graduate Fellowship (RCW). *Corresponding Author: coreywhite@utexas.edu, Phone: 1-336-340-8587 1A. M. Jean-Louis, B. Ayrault, and J. Vargas Phys. Status Solidi B 34 (1969). 2S. Spruytte et al., MRS Internet J. Nitride Semicond. Res. 5 (2000). 3A. J. Ptak et al., J. Cryst. Growth 338 (2012). 4S. J. Maddox et al., 54th Electronic Materials Conf. (2012). 5S. J. Maddox et al., 55th Electronic Materials Conf. (2013). 6M. K. Rajpalke et al., Appl. Phys. Lett. 105 (2014).

Growth Optimization of InSbBi Alloys for Wavelength Extension on InSb

FF: Doping and Stoichiometric Effects on Epitaxial Material

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Growth Optimization of InSbBi Alloys for Wavelength Extension on InSb

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