신소재공학과

Research Highlight



All our smart phones have shiny flat AMOLED displays. Behind each single pixel of these displays hide at least two silicon transistors which are mass-manufactured using laser annealing technologies. While the traditional methods to make them uses temperatures above 1,000°C, the laser technique reaches the same results at low temperatures even on plastic substrates (melting temperature below 300°C). Interestingly, a similar procedure can be used to generate crystals of graphene. Graphene is a strong and thin nano-material made of carbon, its electric and heat-conductive properties have attracted the attention of scientists worldwide.


Prof. Keon Jae Lee's research group at the Center for Multidimensional Carbon Materials within the Institute for Basic Science (IBS) and Prof. CHOI Sung-Yool's team at KAIST discovered graphene synthesis mechanism using laser-induced solid-state phase separation of single-crystal silicon carbide (SiC). This study, available on Nature Communications, clarifies how this laser technology can separate a complex compound (SiC) into its ultrathin elements of carbon and silicon. (http://www.nature.com/articles/ncomms13562)


Although several fundamental studies understood the effect of excimer lasers in transforming elemental materials like silicon, the laser interaction with more complex compounds like SiC has rarely been studied due to the complexity of compound phase transition and ultra-short processing time.

With high resolution microscope images and molecular dynamic simulations, scientists found that a single-pulse irradiation of xenon chloride excimer laser of 30 nanoseconds melts SiC, leading to the separation of a liquid SiC layer, a disordered carbon layer with graphitic domains (about 2.5 nm thick) on top surface and a polycrystalline silicon layer (about 5 nm) below carbon layer. Giving additional pulses causes the sublimation of the separated silicon, while the disordered carbon layer is transformed into a multilayer graphene.


"This research shows that the laser material interaction technology can be a powerful tool for next generation of two dimensional nanomaterials," said Prof. Keon. Prof. Choi added: "Using laser-induced phase separation of complex compounds, new types of two dimensional materials can be synthesized in the future." IBS Prof. Keon is affiliated with the School of Materials Science and Engineering, KAIST and Prof. Choi with the School of Electrical Engineering and Graphene Research Center, KAIST.



laser induced SiC.jpg

High-resolution transmission electron microscopy shows that after just one laser pulse of 30 nanoseconds, the silicon carbide (SiC) substrate is melted and separates into a carbon and a silicon layer. More pulses cause the carbon layer to organize into graphene and the silicon to leave as gas.



Nat.commun.fig1.png

Molecular dynamics simulates the graphene formation mechanism. The carbon layer on the top forms because the laser-induced liquid SiC (SiC (l)) is unstable.

No. Subject Author Date Views
Notice New Anisotropic Conductive Film for Ultra-Fine Pitch Assembly Applications ADMINI 2018.11.30 60
Notice KAIST Introduces Faster and More Powerful Aqueous Hybrid Capacitor ADMINI 2018.11.13 104
Notice Crystal size of organic semiconductors can be controlled using inorganic polymer micropillar-based solution shearing system ADMINI 2018.11.06 253
Notice Mussel-Inspired Defect Engineering Enhances the Mechanical Strength of Graphene Fibers ADMINI 2018.11.06 151
Notice Flexible Piezoelectric Acoustic Sensors for Speaker Recognition ADMINI 2018.10.04 267
Notice Spray Coated Tactile Sensor on a 3-D Surface for Robotic Skin ADMINI 2018.10.04 254
45 Low-power, Flexible Memristor Circuit for Mobile and Wearable Devices ADMINI 2018.06.26 425
44 Levitating 2D Semiconductor for Better Performance ADMINI 2018.08.29 487
43 A High-Performance and Cost Effective Hydrogen Sensor ADMINI 2018.08.03 497
42 Flexible Drug Delivery Microdevice to Advance Precision Medicine ADMINI 2018.08.14 518
41 New Material for Generating Energy-Efficient Spin Currents ADMINI 2018.06.26 540
40 A New Efficient Oxide Coating Technology to Improve Fuel Cells ADMINI 2018.08.03 601
39 Capillary Forces at Work for Lithium-Sulfur Batteries ADMINI 2018.06.26 703
38 KAIST Team Develops Flexible Blue Vertical Micro LEDs ADMINI 2018.06.26 736
37 Platinum Catalyst Has Price Lowed and Durability Doubled ADMINI 2018.06.26 806
36 KAIST Develops Sodium Ion Batteries using Copper Sulfide ADMINI 2018.04.24 1206
35 Researchers develop flexible vertical micro LED file ADMINI 2018.02.07 1257
34 A New Spin Current Generating Material Developed file ADMINI 2017.12.21 1406
33 Lifespan of Fuel Cells Maximized using Small Amount of Metals file ADMINI 2018.01.21 1442
32 Professor Kim Sang Ouk of KAIST participated in editorship of GRAPHIN NEW MATERIALS file ADMINI 2017.10.23 1777