Surface passivation of random alloy AlGaAsSb avalanche photodiode

• Published in: Electronics letters Vol. 59; no. 18
• Main Authors: Cao, Peng, Peng, Hongling, Wang, Tiancai, Srivastava, Vibha, Kesaria, Manoj, You, Minghui, Zhuang, Qiandong, Zheng, Wanhua
• Format: Journal Article
• Language: English
• Published: Stevenage John Wiley & Sons, Inc 01.09.2023; Wiley
• Subjects: Aluminum oxide; Atomic layer epitaxy; Avalanche diodes; avalanche photodiodes; Dark current; Electric fields; Molecular beam epitaxy; Optoelectronic devices; passivation; Passivity; Photodiodes; Silicon nitride; Spectral sensitivity
• ISSN: 0013-5194; 1350-911X
• DOI: 10.1049/ell2.12956

AlGaAsSb attracts significant interest for near‐infrared avalanche photodiodes (APD). The authors report a two‐order reduction in the dark current and a six‐time enhancement of gain in random alloy (RA) AlGaAsSb APD that is surface passivated by conformal coating of Al 2 O 3 via atomic layer deposition (ALD). The dark currents of the APDs with 400‐µm diameter (dry etched) at 90% breakdown voltage (0.9 V br ) are (5.5 ± 0.5) × 10 −5 A, (2.1 ± 0.4) × 10 −5 A, and (6.2 ± 0.8) × 10 −7 A for non‐passivated, Si 3 N 4 passivated, and Al 2 O 3 passivated devices, respectively. The dark current at a gain of 10 for the Al 2 O 3 passivated device is 1 × 10 −8 A which is comparable to the reported value for 100‐µm diameter mesa diodes passivated by SU‐8. Maximum gain values of 6, 12, and 35 were obtained for non‐passivated, Si 3 N 4 passivated, and Al 2 O 3 passivated devices, respectively. Moreover, punch‐through capacitance of 8 pF in a spectral response of 450 to 850 nm was obtained. Thus, Al 2 O 3 passivation can be the best solution for antimonide optoelectronic devices.