Impact of the Ge-Si interfacial barrier on the temperature-dependent performance of PureGaB Ge-on-Si p + n photodiodes

Marković, Lovro; Knežević, Tihomir; Nanver, Lis K.; Attariabad, Asma; Azizur-Rahman, Khalifa M.; Mah, Jasmine J.; Wang, Kang L.; Suligoj, Tomislav (2024) Impact of the Ge-Si interfacial barrier on the temperature-dependent performance of PureGaB Ge-on-Si p + n photodiodes. Optics Express, 32 (20). pp. 35542-35550. ISSN 1094-4087

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Abstract

A temperature-dependent study of the near-infrared (NIR) responsivity of Ge-on-Si photodiodes is presented. The diodes, formed as n-Ge islands within oxide windows on n-Si and capped with Ga and B layers (PureGaB), exhibit low dark current of ∼2 × 10−13 A/µm2 and broadband responsivity. Temperature-dependent measurements reveal an inherent potential barrier at the low-doped n-Ge on the n-Si heterointerface. This leads to a decrease in responsivity with decreasing temperatures for wavelengths above 1100 nm. The Al-migration process along the Ge-Si interface, associated with the sidewall passivation and found to be a means of reducing dark current, increases the barrier height. Irrespective of the barrier height, room-temperature responsivity is fully recovered by applying a reverse bias to lower the interface barrier. In the devices with the highest barrier, the responsivity at 1310 nm increased from 4.8 to 164 mA/W, at 0 V and 18 V reverse bias, respectively. An additional increase in maximum responsivity at 1550 nm is attributed to Al-sidewall passivation leading to a measured responsivity of 126.4 mA/W at 18 V reverse bias.

Item Type:	Article
Uncontrolled Keywords:	Ge-Si interfacial barrier, near-infrared responsivity , Ge-on-Si photodiodes, photodetector
Subjects:	TECHNICAL SCIENCES
Divisions:	Division of Materials Physics
Projects:	Project title Project leader Project code Project type Napredni poluvodički elementi u graničnim područjima upotrebe Tomislav Suligoj IP-2022-10-5294 HRZZ Optoelektrička platforma s mogućnošću razlučivanja jednog fotona za unaprjeđenje optičkih neuronskih mreža Tihomir Knežević NPOO.C3.2.R2-I1.06.0025 EK
Depositing User:	Ivana Vuglec
Date Deposited:	11 Dec 2025 09:12
URI:	http://fulir.irb.hr/id/eprint/10144
DOI:	10.1364/OE.530466

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