Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session F58: Infrared Sensing and ImagingInvited Live Undergrad Friendly
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Sponsoring Units: FIAP Chair: Carola Emminger, New Mexico State University |
Tuesday, March 16, 2021 11:30AM - 12:06PM Live |
F58.00001: GeSn alloys with mid-IR direct band gaps Invited Speaker: Jose Menendez GeSn alloys represent the only group IV system with an expected direct band gap over a broad range of compositions. Since the indirect to direct transition takes place at rather modest (~8%) Sn concentrations, research interest has focused on this dilute alloy regime with band gaps in the near-IR. However, the expected electronic structure of GeSn is similar to that of HgCdTe, featuring a continuum of direct band gaps that reach a value of zero. GeSn systems with direct band gaps in the mid-IR and beyond require much higher Sn concentrations, which are not obviously attainable due to the thermodynamic metastability of the alloy. Fortunately, this fundamental limitation doesn’t appear to be unsurmountable, as several reports on high-Sn alloys have already appeared in the literature, although the materials were not always suitable for optical measurements. In this presentation I discuss recent optical characterization work on GeSn alloys with Sn concentrations as high as 36%. These materials were synthesized directly on Si substrates using custom CVD methods that combine stannane with polygermanes, making it possible to tune the Sn concentration over a much broader range than previously possible. These materials are found to have direct band gaps approaching 0.15 eV (~ 8 μm), well within the mid-IR spectral range. |
Tuesday, March 16, 2021 12:06PM - 12:42PM Live |
F58.00002: Depth Sensing Photonics for Mobile Handset, Automotive and other Consumer Applications Invited Speaker: Brandon Collings Machine learning and predictive algorithms are increasingly providing new opportunities for technology to directly participate in our interaction with the physical world around us. A crucial element of this interaction is the detailed digital characterization of that physical environment as an input to these algorithms. While digital visible light cameras have advanced dramatically for compact consumer applications, optical sensor systems able to add accurate depth measurements to 2D images within practical consumer environments are being developed to enable new and enhanced consumer applications. Primary examples of these sensor driven applications include biometric authentication on mobile phone handsets and secure access points as well as LIDAR scene mapping for autonomous vehicles and robotic machines. This presentation will provide an overview of the architectures of these 3D sensor systems, their underlying enabling photonic technologies, including advanced VCSEL devices and array formats, narrow linewidth semiconductor lasers, MEMS, and photonic sensors, and how such complex technological solutions are being brought to the consumer market. |
Tuesday, March 16, 2021 12:42PM - 1:18PM Live |
F58.00003: Advances in III-V Semiconductor Unipolar Barrier Infrared Photodetectors Invited Speaker: David Ting The past decade has seen accelerated progress in III-V semiconductor infrared photodetector technology. The advent of the unipolar barrier infrared detector device architecture has in many instances greatly alleviated generation-recombination (G-R) and surface-leakage dark current issues that had been problematic for many III-V photodiodes. Meanwhile advances in a variety type-II superlattices (T2SLs) such as InGaAs/GaAsSb, InAs/GaSb, and InAs/InAsSb, as well as in bulk III-V material such as InGaAsSb and metamorphic InAsSb, have provided continuously adjustable cutoff wavelength coverage from the short wavelength infrared (SWIR) to the very long wavelength infrared (VLWIR). The confluence of these developments has led to a new generation of versatile, cost-effective, high-performance infrared detectors and focal plane arrays (FPAs) based on robust III-V semiconductors, providing a viable alternative to HgCdTe (MCT). In particular, InAs/InAsSb T2SL detectors has enabled FPAs with significantly higher operating temperature than the market-leading mid-wavelength infrared (MWIR) InSb FPAs. |
Tuesday, March 16, 2021 1:18PM - 1:54PM Live |
F58.00004: Impact Ionization Engineering in Antimonide Heterostructures for Avalanche Photodiodes Invited Speaker: Sanjay Krishna Development of low noise avalanche photodiodes (APDs) in the short wave infrared (1.5-3 microns) and mid-wave infrared (3-5 microns) requires engineering of the impact ionization process. State of the art APDs are based on based on interband transitions in mercury cadmium telluride (MCT, HgCdTe) with large multiplication gains and low excess noise factors due to the favorable bulk bandstructure that promotes single carrier impact ionization. We have investigated the multiplication characteristics of three different multipliers on InP substrate (AlGaInAs (M1), AlGaAsSb (M2) and AlInAsSb (M3)). We have demonstrated decrease in the excess noise factors using ternary superlattices and extremely low excess noise factors (k~0.01) and low dark current density (~10 μA/cm2 ) at 300K. We will discuss the research challenges associated with the design, growth, fabrication and radiometric characterization of these APDs and the potential for the development of these critical APD components for LiDAR and active remote sensing and imaging systems. |
Tuesday, March 16, 2021 1:54PM - 2:30PM Live |
F58.00005: Minority carrier lifetime of strain-balanced InGaAs/InAsSb superlattices and associated detector performance gains in mid-wave infrared space applications Invited Speaker: Preston T. Webster Being the ultimate high ground, space-based surveillance has long been a critical aspect of every |
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