Simulation and modelling of superlattice infrared photon sensors

Date

2023-9-07

Author

Öztürk, Mustafa Can

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Type-II superlattice detectors have the potential to surpass conventional HgCdTe photodiodes for long wave infrared sensing. High uniformity, ease of production, relatively low production cost and substrate availability make type-II superlattice detectors more appealing over HgCdTe photodiodes. Recent studies have shown that Ga-free InAs/InAsSb superlattices might be a solution to the problem of short minority carrier lifetimes in superlattice detectors. This study focuses on the modelling and simulation of a pBn detector structure with a 5 μm thick 90 Å InAs / 25 Å InAs0.5Sb0.5 superlattice absorber layer for long wave infrared sensing. As the barrier, a 0.2 μm thick AlAs0.15Sb0.85 layer was used to suppress dark current mechanisms such as generation recombination, trap assisted tunnelling and band to band tunnelling. A broadband long wave infrared responsivity spectrum, which is measured from 10% of the peak current responsivity, was obtained between 8 – 9.92 μm. At 77 K, a peak current responsivity of 2.77 A/W at 8.75 μm wavelength was recorded from the simulation results. This peak current responsivity corresponds to a quantum efficiency of 39.3%. A dark current density of 5.52×10-5 A/cm2 was obtained, which is comparable to conventional HgCdTe photodiodes. Relatively low quantum efficiency remains to be a bottleneck for superlattice detectors. Compared to HgCdTe photodiodes, the simulated superlattice structure has comparable levels of dark current density and considerably lower quantum efficiency. However, it is shown that with the broadband responsivity spectrum of the device, it may very well be an alternative to HgCdTe photodiodes.

Subject Keywords

Type-II superlattice detectors, InAs/InAsSb, long wave infrared sensing

URI

https://hdl.handle.net/11511/105538

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Graduate School of Natural and Applied Sciences, Thesis