MOCVD growth of LWIR InAs/InAsSb Type-II superlattices for focal plane array applications
Abstract
Inexpensive high-performance large-format imaging sensors are highly needed for the next generation of the ArmyÕs persistent surveillance applications. Sb-based Type-II superlattices (T2SLs) represent the most promising material system capable of delivering a more manufacturable and affordable large-format focal plane array technology than the current technology. Despite its rapid development, there is still a large gap between the theoretical capabilities of this material system and the experimental performance of the detectors. Despite its rapid development, there is still a large gap between the theoretical capabilities of this material system and the experimental performance of the detectors. This is because InAs/GaSb based T2SLs shows limited minority carrier lifetime which is partially attributed to acceptor-like defects in GaSb. With Gallium being the suspected culprit of the short minority carrier lifetime, InAs/InAs1-xSbx T2SLs has the potential to achieve longer minority carrier lifetimes. Compared to the complex interfacial schemes during the growth of InAs/GaSb T2SLs, InAs/InAs1-xSbx T2SLs can be grown on GaSb substrate in a strain balanced manner. InAs/InAs1-xSbx T2SLs has relatively simple interface structure with only one changing element (Sb), which reduces the complexity of interface control during growth. Improvement in material quality and processing technique, as well as evolutionary modifications in device architecture have demonstrated the advantages of InAs/InAs1-xSbx T2SLs and proven it as a viable candidate for the next generation infrared imaging. Yet, the performance of this material system has not reached its limits. In this project, we will study metal-organic chemical vapor deposition (MOCVD) growth of strain-balanced InAs/InAs1-xSbx T2SLs for LWIR detection and imaging. During MOCVD growth, hydrogen is used as carrier gas, which is helpful to reduce the spitting defects. Meanwhile, the MOCVD growth chamber can be cleaned easily after each growth, which will apparently reduce the growth memory effect. Therefore, it is expected to have better InAs/InAs1-xSbx T2SLs material quality by MOCVD than by MBE. In addition, MOCVD growth has advantages of high growth rate and easy maintenance, which is crucial for high throughput and low cost production. Realization of MOCVD growth of T2SLs will make it lower cost, more affordable and have more products. Combined with MOCVD growth and InAs/InAs1-xSbx T2SLs design, it is expected to achieve low cost, high performance and large format imaging sensors.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 08, 2019
- Source ID
- W911NF1810402
Entities
People
- Manijeh Razeghi
Organizations
- Army Contracting Command
- Northwestern University
- United States Army