Carbon nanotubes (CNT) with one-dimensional structural characteristics has been a star material in the nano material field since it was first prepared and reported in the early 1990 s. After nearly 30 years of development and research, at present, it has shown great application potential in many fields. At the same time, with the progress and development of high-end technology, the demand for field effect transistors (FETs) with high density, high performance and high energy efficiency in industrial production is becoming more and more urgent. However, the currently used metal-oxide semiconductor field effect transistor (MOS)FETs is difficult to conform to the future development trend of high integration and miniaturization of integrated circuits (IC), so it is urgent to develop new FETs. On May 22, 2020, the latest issue of Science magazine published three consecutive articles on CNT's research progress in FETs field! Here, the editor will take a look at what breakthroughs have been made!
1. High specification and high density carbon nanotube semiconductor array
CNT has the characteristics of one-dimensional structure and adjustable nanoscale size, so it has been studied to replace silicon-based FETs long ago. However, due to the purity of CNT, the density and arrangement regularity of CNT in the prepared FETs cannot be solved all the time, thus limiting the large-scale preparation and application of CNT-based FETs. In order to solve this problem, the research team of academician Peng Lianmao of Peking University, together with the research team of Professor Zhang Zhiyong, firstly developed the method of multiple dispersion and sorting to prepare high purity CNT for FETs; then the CNT array with good arrangement and adjustable density (the number of arrangement per Micron is between 100 and 200) is prepared on the 10cm silicon wafer substrate by the method of size limitation and automatic arrangement. Under the condition of the same gate length, the FETs prepared based on the whole series of CNT shows better performance than the commercial silicon-based FETs-under the voltage condition of 1V, the on current reaches 1.3 mA · um-1, and the cross-conduction reaches a record of 0.9 mS · um-1. At the same time, a low room temperature threshold swing (<90mV/10 years) can be maintained when ionic liquid is used as the gate. In addition, the top gate five-stage ring oscillator manufactured in batches shows that the highest maximum oscillation frequency can be greater than 8 GHz. Therefore, this field effect transistor based on CNT array shows great application potential in the future microelectronics field. The research results were published in Aligned with the title "density semiconducting carbon nanotube arrays for high, high-Science-performance electronics.
Original link: https://science.sciencemag.org/content/368/6493/850
2. Prepare accurate carbon nanotube arrays in three-dimensional DNA nanometer grooves
as mentioned above, the difficulty of preparing CNT-based field effect transistors lies in the high density and high normalization of CNT arrays. In order to solve this problem, Yin Peng (graduated from Peking University) from Harvard University and Harvard Medical School, professor Wei Sun's research team cooperated to develop a supramolecular assembly method to prepare CNT arrays with high density and high normalization. Specifically, the researchers first used the self-assembly of single-stranded DNA to construct grooves with regular array structure, and then "specifically modified" the surface of CNT ", make these modified CNT lie accurately into the previously designed groove, then we can get CNT array with spacing less than 10.4 nm, deviation angle less than 2 ° and assembly efficiency more than 95%. The study, entitled "Precise pitch-scaling of carbon nanotube arrays within three-dimensional DNA nanotrenches", was published in the Science.
Original link: https://science.sciencemag.org/content/368/6493/874
3. Preparation of high performance CNT field effect transistors by DNA oriented nanotechnology
compared with the lithography method currently in use, the semiconductor nano-arrays prepared by biological processing method show smaller channel spacing. However, the metal ions and sub-micron size characteristics in the biological lattice lead to poor transmission performance and reduced uniformity of large-area arrays. In order to solve this problem, the research team of Professor Sun Wei of Peking University and Professor Zhu Zhi of Xiamen University cooperated to use the parallel CNT array prepared by DNA template method as the model system, developed a rinsing-after-fixing method the method of improving the key transmission performance index of effect transistor based on CNT array by more than 10 times (compared with the previous biological template field effect transistor). In the study, the author used a space-limited method to assemble a CNT array up to centimeter level in PMMA cavity. On the self-assembly interface of high-performance electronics and biomolecules, this method can make it possible to produce scalable biological template electronic products. The study was published in DNA-directed with the title "effect transistors nanofabrication of high-performance carbon nanotube field-Science.
