Metal-germanium-metal photodetector grown on silicon using low temperature RF-PECVD

Ghada Dushaq, Ammar Nayfeh, Mahmoud Rasras, Mahmoud Rasras

Research output: Contribution to journalArticlepeer-review


In this paper, germanium metal-semiconductor-metal photodetectors (MSM PDs) are fabricated on Si using a low-temperature two-step deposition technique by RF-PECVD. The photodetectors are optimized to effectively suppress the dark current through the insertion of n-type a-Si:H interlayer between the metal/Ge interface. Tuning the Schottky Barrier Height (SBH) by inserting different thickness of the interlayer is investigated. Results revealed that SBH for electrons and holes can effectively be enhanced by 0.3eV and 0.54eV, respectively. Furthermore, the dark-current (IDark) is suppressed significantly by more than four orders of magnitude. The measured IDark is ~76 nA for an applied reverse bias of 1.0 V. Additionally, the Ge MSMs structure exhibited a photo responsivity of 0.8A/W at that bias. The proposed low-temperature (<550°C) Ge-on-Si MSM PD demonstrates a great potential for high-performance Ge-based photodetectors in monolithically integrated CMOS platform.

Original languageEnglish (US)
Pages (from-to)32110-32119
Number of pages10
JournalOptics Express
Issue number25
StatePublished - Dec 11 2017

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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