Recent advancements in photodetection using 2D materials suggest significant improvements in the performance of photodetectors. Among these, graphene field-effect transistors (GFETs) have demonstrated promising enhancements in photodetection, characterized by low noise, broad-spectrum response, high responsivity, and fast response [46, 126]. These photodetectors utilize graphene as the active channel, with graphene deposited on an insulating layer and semiconductor substrate. The contact of graphene with an insulator/semiconductor structure induces an interfacial potential to trap one type of photo-generated carrier at the interface. The trapped charge carriers induce opposite carriers in the graphene channel through the capacitive coupling effect. Due to a long lifetime of trapped carriers, the induced carriers in the graphene channel circulate multiple times under a given bias between the source and drain contacts, generating a photocurrent with high gain. Here, we explore GFET photodetectors fabricated on p-GaAs and p-Si wafers at room temperature. The photodetectors achieve a high gain. The photocurrent is generated due to the photogating effect.
In this work, we explore GFET photodetectors fabricated on p-GaAs and p-Si wafers at room temperature. The photodetectors achieve a high gain and high responsivity of 106 (A/W) under the above bandgap excitation and can detect light below the bandgap illumination for both p-doped substrates. NEP and D* values of these detectors have been characterized along with response time characteristics. The NEP and Dā values for both detectors are around 10ā15 W/ā and 1012 Jones respectively, indicating a sensitive photodetection. The response time characterization suggests the rise and decay time depends on incident power. These results provide us with a deeper insight into the photodetection of the GFETs from the ultraviolet to near-infrared region. / Master of Science / Photodetectors have numerous applications in our daily lives, such as optical sensors in mobile phones, telecommunications, and biological imaging. However, current photodetection technologies often struggle to meet the increasing demands of modern equipment. These technologies require improving the existing photodetectors so that they can operate at exceptionally high speeds with low noise. Graphene is a highly sensitive material, that has shown significant potential for photodetection due to its fascinating optoelectronic and mechanical properties. In this study, we fabricated two field effect transistors on two semiconductor materials of different bandgaps with a single layer of graphene added on top of the substrate/insulator layer for photodetection. Specifically, we investigate the performance of GaAs and Si substrates to understand how varying the substrate can affect photodetection so that it can open up possible routes to future applications.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/121108 |
| Date | 10 September 2024 |
| Creators | Jahan, Nusrat |
| Contributors | Physics, Nguyen, Vinh, Pleimling, Michel Jean, Heremans, Jean Joseph |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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