| Summary: | 碩士 === 國立中央大學 === 照明與顯示科技研究所 === 105 === A graphene-germanium-graphene photodetector (GSG PD) is investigated in this research with transparent graphene electrodes. Germanium is a good absorption coefficient material in near infrared wavelength including 850 nm, 1310 nm and 1550 nm for optics communication. Generally, the metal electrode was utilized for the photodetector applications. However, there were a lot of light loss for the non-transparency. In recent years, graphene has been found to be a good transparent conductive film (TCF) with a two-dimensional monolayer composed by sp2-bonded carbon atoms. Due to its exceptional electrical conductivity and high optical transmittance especially including near infrared, graphene is one of the promising candidates for TCFs. Therefore, the higher photo-current and responsivity of the device with graphene can be achieved.
In this investigation, interdigitated graphene electrodes were applied to a near infrared photodetector. We used a n-type germanium as the substrates and graphene layers as the interdigitated electrodes of the photodetector. The interdigitated graphene electrodes were prepared by chemical vapor deposition (CVD), and transferred to the substrate first, then patterned by O2 plasma. The responsivity of the n-Ge PD was 0.39 A/W, 0.59 A/W and 0.77 A/W for the wavelength 850 nm, 1310 nm and 1550 nm of the incident light, separately. And the photo to dark current ratio was over three orders.
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