University of California, Riverside

Department of Electrical and Computer Engineering



Nature Nanotech News Highlighted Transistors Built at UCR Electrical Engineering Department


Nature Nanotech News Highlighted Transistors Built at UCR Electrical Engineering....
 

Nature nanotechnology news highlighted novel low-noise top-gate graphene transistors built at the Department of Electrical Engineering, University of California - Riverside (UCR). A team of researchers led by an electrical engineering professor Alexander Balandin designed, built and demonstrated the first top-gate single-atomic-layer graphene transistor, which satisfies the low-noise requirements for practical applications in electronics and communications. A set of transistors were fabricated at UCR clean room using the electron beam lithography and atomic layer deposition from graphene, a single atomic layer of carbon atoms bound in honeycomb lattice. These devices were tested both in the Nano-Device Laboratory (NDL) of professor Balandin and in the Center for Integrated Electronics of the Rensselaer Polytechnic Institute (RPI). The transistors, which were built by PhD candidate Guanxiong Liu, had a "conventional" bottom gate and, in addition to it, a top gate separated from the graphene channel by a special electric insulator - hafnium oxide - recently introduced by the electronic industry in conventional transistors. In a set of tests at RPI, conducted by the top noise experts, it was determined that the single-atomic-layer graphene transistors designed and built at NDL had unusually low levels of the electronic flicker noise. For any transistor to be useful for communications or information processing, the level of the electronic low-frequency noise, also referred as flicker noise, has to be reduced to an acceptable level. Although modern electronic devices such as cell phones operate at very higher frequencies, the low-frequency noise is extremely important. Due to unavoidable non-linearity in devices, the low-frequency noise up-converts to higher frequency, and contributes to the phase noise of the system, thus limiting its performance. The results obtained in UCR and RPI are crucial for practical applications of graphene.  

GuanxiongLiu

Photo: Guanxiong Liu, PhD candidate in Balandin group, who built the advanced graphene transistors, sits in front of Raman spectrometer, which was used to verify the number of atomic layers in graphene materials.

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