Bandgap Engineering and Short-Wavelength Infrared Detection of InGaAs/GaAsSb Superlattices Lattice-Matched to InP

• Published in: Journal of electronic materials Vol. 51; no. 9; pp. 4703 - 4713
• Main Authors: Gil, Armando, Phillips, Jamie, Ettenberg, Martin H., Babikir, Nuha A.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.09.2022; Springer Nature B.V
• Subjects: 2021 U.S. Workshop on Physics and Chemistry of II-VI Materials; Absorbers; Absorptivity; Bias; Characterization and Evaluation of Materials; Chemistry and Materials Science; Current voltage characteristics; Dark current; Design; Design optimization; Diffusion length; Efficiency; Electronics and Microelectronics; Energy; Energy gap; Energy levels; Engineering; Indium phosphides; Instrumentation; Lattice matching; Materials Science; Mathematical analysis; Minority carriers; Molecular beam epitaxy; Optical and Electronic Materials; Optical properties; Optical transition; P-i-n photodiodes; Quantum efficiency; Sensors; Simulation; Solid State Physics; Superlattices; Temperature dependence; Thickness; U.S. Workshop on the Physics and Chemistry of II-VI Materials 2021; Wave functions; Dark current; optical absorption; SWIR; type-II superlattice; InGaAs/GaAsSb; quantum efficiency
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-022-09745-x

This study investigates the effective bandgap and optical absorption properties of type-II superlattice (T2SL) InGaAs/GaAsSb structures lattice-matched to InP in the short-wavelength infrared (SWIR) regime. One-dimensional eight-band k → · p → calculations were used to calculate quantum-confined energy levels and optical absorption coefficients of symmetric and asymmetric T2SL with varying period thickness. Optical and electrical data were measured from p - i - n photodiodes fabricated with symmetric period thicknesses of 10 nm and 5.8 nm. Smaller period thickness shows substantially increased quantum efficiency, which is believed to be related to increased electron–hole wavefunction overlap for the indirect type-II optical transition and corresponding increase in optical absorption strength. The quantum efficiency (QE) spectra for front-side illuminated devices exhibit a turn-on bias, which may be due to an undepleted absorber at zero bias and a minority carrier diffusion length comparable to, or less than, the absorber thickness. Extractions of optical absorption coefficients from the QE agree with the calculated energies for T2SL optical transitions and absorption coefficient near the band edge in the range of 10 3 – 10 4 cm - 1 . Temperature-dependent current–voltage characteristics show dark current densities competitive with extended-range InGaAs photodiodes, but device design and fabrication processes require optimization in order to approach the high performance demonstrated by InGaAs photodiodes.