Novel Metamorphic Heterostructures for Long Wave Infrared Optoelectronics
Technical Report,06 Apr 2016,05 Oct 2019
Research Foundation of SUNY at Stony Brook Stony Brook United States
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Major Goals III-V semiconductor compound barrier heterostructures for infrared optoelectronics are considered to be an attractive alternative to II-VI HgCdTe technology, mainly because of the lower cost, ease of scaling to large format arrays and better uniformity 1. Due to the stronger, less ionic chemical bond, III-V semiconductors are more robust and stable than their II-VI equivalents. During SPIE Defense and Security Conference in April 2017, Anaheim, California, the spectacular results of the Vital Infrared Sensor Technology Acceleration VISTA US government program in developing Type-2 Strained Layer Superlattice SLS Focal Plane Array of small pixel detectors have been demonstrated. Optoelectronic devices with Type-2 InAsSbInAs Ga-free SLS absorbers grown lattice matched to GaSb substrate outperform previously employed technologies in mid-wave infrared MWIR wavelength range. At the same time, extension of Type-2 Ga-free SLS operation to Long Wave Infrared Range LWIR meet fundamental challenges 2. Reduction of the energy gap in this system and increase of cut-off wavelength, respectively, is obtained with increase of Sb composition. Following this approach for reliable device operation, the practical Sb composition in InAsSb is limited to 40 defined by the maximum 2 strain in InAsSb layer grown lattice matched to GaSb. This leads to an increasing challenge to obtain the device cut-off wavelength beyond 12 um. A consequence of large Sb composition in InAsSb layers is an increase of the thickness of InAs layers dictated by required strain balancing with growth on the GaSb platform. Elevated thickness of InAs layers results in reduction of electron hole overlap lower absorption and impeded hole transport shorter minority hole diffusion length in the growth direction. Both of the factors result in reduction of the critical parameter, quantum efficiency.
- Solid State Physics
- Electrooptical and Optoelectronic Devices