Quantum cascade lasers and detectors- a path to quantum cascade interband detectors (QCIDs)
Abstract
The recent development of InAs-AlAsySb1-y quantum cascade detectors (QCDs) on InAs (1) and GaSb substrates (2) have expanded the range of mid-infrared (MIR) intersubband (ISB) detectors. QCDs are high-speed room-temperature photovoltaic detectors that use unipolar ISB transitions to detect MIR and THz (Far IR) light (3, 4). The possible detection wavelengths are determined by the conduction band offset (CBO) between the barriers and wells, and not limited to the semiconductor band gap. The optical transition levels and the carrier extraction levels are designed through band structure engineering. This allows great freedom in active region design and the ability to cover a wide range of wavelengths (energies). Additionally, QCDs can be optimized to work at high-frequencies, up to 50 GHz, a result of the subpicosecond lifetimes of the intersubband states (5). The InAs-AlAsySb1-y material system has a CBO of 2.1 eV at the Gama-point and 1.35 eV at the L-valley. Since the m x e is inversely proportional to the oscillator strength of the optical transition, InAs quantum wells (0.23m x e) show improved absorption over InGaAs- (0.43m x e) and GaAs-based (0.67m x e) ISB detectors (2, 6). The interband absorption in GaAs- and InP-based QCDs occurs at significantly higher energies than for the ISB transition, due to the type-I alignment of the well and barrier material, the minimum level of the conduction band, and the larger band gap of the two material systems. However, on GaSb and InAs substrates, the type-II band alignment of InAs-AlAsySb1-y enables interband absorption at E_photon greater tahn or equal to E_ISB. Thus enabling a new type of zero-bias photovoltaic MIR sensor, the quantum cascade interband detector (QCID). This is a broadband absorber and potentially more efficient than QCDs at similar wavelengths. In this project we will study the design, physics, growth, and characteristics of the interband transitions in a GaSb-based QCD extractor region forming the novel QCID.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 22, 2024
- Source ID
- FA86552317070
Entities
People
- Aaron Andrews
Organizations
- Air Force Office of Scientific Research
- TU Wien
- United States Air Force