Quantum Cascade Detectors on Silicon Substrates (QCDS)
Abstract
Quantum cascade detectors (QCDs) are high-speed room-temperature photovoltaic detectors that use unipolar intersubband (ISB) transitions to detect mid-infrared (MIR) and terahertz (THz) light. The possible detection wavelengths are determined by the conduction band offset (CBO) between the barriers and wells, and are not limited to the semiconductor band gap. The optical transition levels and the carrier extraction levels are designed through band structure engineering. The recent development of InAs-AlAsySb1-y QCDs on InAs and GaSb substrates by Technische Universitat Wien (TUW) have expanded the range of MIRs ISB detectors. The InAs-AlAsySb1-y material system has a CBO of 2.1 eV at the Γ-point and 1.35 eV at the L-valley. Since the electron effective mass m*e is inversely proportional to the oscillator strength of the optical transition, InAs quantum wells (0.23m∗e) show improved absorption, lower noise, and increased responsivity over InGaAs- (0.43m∗e) and GaAs-based (0.67m∗e) ISB detectors [4, 5]. Silicon is a earth-abundant material (27.7 percent of earth crust), offers advantageous economic, electronic, mechanical and thermal properties, and it is the foundation of the complementary metal-oxide-semiconductor (CMOS) technology. For this reason, in recent years silicon photonic devices are of great research interest. For instance, resonators, modulators, couplers, multiplexers, and frequency combs have been demonstrated. However, silicon suffers the lack of a direct band-gap, required for most optical applications. Additionally, high-speed MIRs photodetectors rely on ISBs transitions or type-II interband transitions, which have not been demonstrated for silicon-based photodetectors.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 06, 2025
- Source ID
- FA86552517004
Entities
People
- Aaron Andrews
Organizations
- Air Force Office of Scientific Research
- United States Air Force