BITS Faculty Publications
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Item Porphyrin induced changes in charge transport of graphene FET(IEEE, 2016) Rao, V. RamgopalThe transport properties of back-gated graphene field effect transistors (GFETs) can be tuned via chemical doping. In this study, we report alteration of charge transport properties of GFET via 5-(4-hydroxyphenyl)-10,15,20-tri-(p-tolyl) zinc(II) porphyrin (Zn(II)-TTPOH) and its free base counterpart. We propose that, the porphyrin induces p-type doping in graphene.Item Application of Mono Layered Graphene Field Effect Transistors for Gamma Radiation Detection(IEEE, 2018-10) Rao, V. RamgopalIn this work, we report the application of graphene field effect transistors (GFETs) as a gamma radiation sensor. The GFETs were irradiated at room temperature by 60 Co gamma radiation source for 10 kGy and 20 kGy gamma dose. The Electrical measurements and Raman spectroscopy showed that gamma radiation induced p-doping in graphene. Large positive shifts in Dirac point and significant degradation in electron mobility were observed post-gamma irradiation. Thus modulation in transport properties of GFETs was utilized here to measure the absorbed gamma radiations. We propose, a GFET based radiation detector with high sensitivity of + 113 V for 20 kGy gamma dose operating in ambient condition.Item Modification of Electronic Properties of Graphene with Porphyrin Self-Assembled Monolayers and Photoinduced Interactions(American Scientific Publishers, 2012-07) Rao, V. RamgopalSolution processable reduced graphene oxide (RGO), with its unique electrical and structural properties is being considered in large scale device fabrication. The research developments in the formation and characterization of nanoelectronic devices with self-assembled monolayers (SAMs) of porphyrin can have foundations for future high speed electronics, alternative energy sources and sensors. In this work, we present the effect porphyrin monolayer functionalization on the electronic properties of RGO. Electrical transport measurements show that this dipolar monolayer on RGO induces doping and the capacity to tune the electronic properties of RGO may have important applications in future graphene devices, sensors and energy harvesting. Also, carrier transfer from excited zinc porphyrin molecules to carbon-based nanostructures is demonstrated on transistors comprising physiosorbed RGO on zinc porphyrin SAM.Item A Roadmap for Disruptive Applications and Heterogeneous Integration Using Two-Dimensional Materials: State-of-the-Art and Technological Challenges(ACS, 2021-08) Rao, V. RamgopalThis Mini Review attempts to establish a roadmap for two-dimensional (2D) material-based microelectronic technologies for future/disruptive applications with a vision for the semiconductor industry to enable a universal technology platform for heterogeneous integration. The heterogeneous integration would involve integrating orthogonal capabilities, such as different forms of computing (classical, neuromorphic, and quantum), all forms of sensing, digital and analog memories, energy harvesting, and so forth, all in a single chip using a universal technology platform. We have reviewed the state-of-the-art 2D materials such as graphene, transition metal dichalcogenides, phosphorene and hexagonal boron nitride, and so forth, and how they offer unique possibilities for a range of futuristic/disruptive applications. Besides, we have discussed the technological and fundamental challenges in enabling such a universal technology platform, where the world stands today, and what gaps are required to be filled.