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Abstract GeSn photodetectors monolithically grown on Ge virtual substrates demonstrate mid‐wave infrared (MWIR) detection at room temperature. The lattice mismatch between GeSn and Ge causes dislocations and compressive strain, creating leakage pathways and unwanted indirect band transitions. Designed thin Ge0.91Sn0.09triple‐step buffer layers of ≈175 nm total thickness reduce dislocations and enable full relaxation, showing 100% lattice relaxation and smooth surface roughness of 0.83 nm with shorter auto‐correlation length in surface morphology compared to single‐step buffers. Ge1‐xSnxphotodetectors (x= 0.09, 0.12, and 0.15) on triple‐step buffers withn‐i‐pconfigurations achieve lattice strain relaxations of 99%, 88%, and 80%, respectively. Ge0.91Sn0.09and Ge0.88Sn0.12show gradual variation in auto‐correlation amplitude, while Ge0.85Sn0.15shows an increase due to lattice mismatch. Shockley–Read–Hall recombination current dominates at low reverse bias due to mismatch‐induced dislocations, while band‐to‐band tunneling current dominates at higher reverse bias due to narrowing bandgap under strong electric fields. The photodetectors show extended spectral response with increasing Sn composition ofi‐GeSn active layer sandwiched by barriers. Ge0.88Sn0.12and Ge0.85Sn0.15exhibit extended wavelength cut‐offs of 3.12 and 3.27 µm at room temperature, demonstrating significant potential for silicon‐based MWIR applications.
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AlInAsSb Geiger-mode SWIR and eSWIR SPADs with high avalanche probability
Single-photon avalanche diodes (SPADs) that are sensitive to photons in the Short-wave infrared and extended short-wave infrared (SWIR and eSWIR) spectra are important components for communication, ranging, and low-light level imaging. The high gain, low excess noise factor, and widely tunable bandgap of AlxIn1-xAsySb1-yavalanche photodiodes (APDs) make them a suitable candidate for these applications. In this work, we report single-photon-counting results for a separate absorption, charge, and multiplication (SACM) Geiger-mode SPAD within a gated-quenching circuit. The single-photon avalanche probabilities surpass 80% at 80 K, corresponding with single-photon detection efficiencies of 33% and 12% at 1.55 µm and 2 µm, respectively.
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- Award ID(s):
- 1842641
- PAR ID:
- 10484487
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Optics Express
- Volume:
- 32
- Issue:
- 2
- ISSN:
- 1094-4087; OPEXFF
- Format(s):
- Medium: X Size: Article No. 2106
- Size(s):
- Article No. 2106
- Sponsoring Org:
- National Science Foundation
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