Metal-semiconductor-metal traveling-wave photodetectors

Jin Wei Shi, Kian Giap Gan, Yi Jen Chiu, Yen Hung Chen, Chi Kuang Sun, Ying Jay Yang, John E. Bowers

Research output: Contribution to journalArticlepeer-review

84 Scopus citations


We demonstrate a novel type of traveling wave photodetector: "metal-semiconductor-metal traveling-wave photodetector" (MSM-TWPD). Demonstrated devices were fabricated using low-temperature grown GaAs (LTG-GaAs). In order to achieve high internal quantum efficiency, the narrow spacing between electrodes was fabricated by the self-aligned process without e-beam lithography. Electrooptical sampling measurement results at different optical pumping level are reported. Ultrahigh bandwidth (0.8-ps, 570-GHz transform bandwidth) performance was observed even under high optical power illumination (∼1.8 mW) with 8.1% net quantum efficiency. Compared with LTG-GaAs-based p-i-n TWPD and vertically illuminated MSM photodetector (PD), this novel TWPD has higher output saturation current with near terahertz electrical bandwidth, better quantum efficiency, and can be easily fabricated and integrated with other microwave devices. It thus promises the application in high-power distributed PD array or terahertz signal generation.

Original languageEnglish
Pages (from-to)623-625
Number of pages3
JournalIEEE Photonics Technology Letters
Issue number6
StatePublished - Jun 2001


  • Low-temperature-grown GaAs
  • Metal-semiconductor-metal photodetectors
  • Self-alignment
  • Traveling-wave photodetectors
  • Ultrahigh-speed photodetectors


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