Novel Metamorphic Heterostructures for Long Wave Infrared Optoelectronics
Abstract
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 InAsSb/InAs (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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 05, 2020
- Accession Number
- AD1096924
Entities
People
- Dmitri Donetski
- Gregory Belenky
- Sergey Suchalkin