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[Press Release] Professor Byoung Hun Lee"s research team has developed the first graphene-based complementary ternary logic device
- 엘리스 리
- REG_DATE : 2016.12.29
- HIT : 942
Professor Byoung Hun Lee"s research team has developed
the first graphene-based complementary ternary logic device
[Figure 1] Characteristics of three-stage inverter using graphene-based logic device. (B) The characteristics of the inverter circuit were simulated under the condition of VDD = 2V. (A) The inverter circuit was constructed by connecting a complementary striking logic device (Pt, p-type: Al) It is possible to realize the characteristics of the triple inverter with only two elements.
□ Gwangju Institute of Science and Technology (GIST) Professor Byoung Hun Lee"s research team has succeeded in developing a complementary ternary logic device using graphene material that allows for the development of ternary-based computers *.
∘ Application of this innovative technique is expected to contribute greatly to solving the problem of increased power consumption in binary based computers.
* Ternary-based computers: Computers that process information with three signals: 0, 1, 2, or -1, 0, 1, unlike binary, which processes information with two signals
□ As silicon semiconductor devices become finer, current leakage, production cost, and power consumption increase, and enormous power is consumed to perform complex operations required by artificial intelligence. For this reason, the necessity of computers to use new electronic devices and computing methods using new nano- materials has been constantly researched.
∘ Ternary-based circuits are simpler in operation and circuitry than conventional binary-based circuits in conventional computers, and the number of devices used is reduced to about one-third, which is receiving attention as a possible technological solution to reduce power consumption. However, ternary logic devices remain in the realm of theoretical research because it has only been implemented in one device, and efforts to implement it in other semiconductor devices has not been successful because of problems with mass production.
[Figure 2] Grain-based ternary logic device structure and electrical characteristics. (A) Three-dimensional structure of graphene-based ternary logic device and (b) SEM photograph. (C) The resistance change of graphene-based ternary logic device with voltage. Due to the partially formed metal band, the Fermi level of graphene is changed to form a PNP or NPN type channel shape. The graph shows the Fermi level change of the graphene channel with voltage. (D) Current change due to graphene-based ternary logic device voltage. Three currents (I0 ", I1", I2 ") were observed in one device due to the partially formed metal strips.
The research team has developed a graphene-based triple logic device capable of complementary logic circuits * that can achieve three different currents in a single device, as well as three logic levels for positive and negative voltages, respectively.
* Complementary logic circuit: Logic circuit design technology that minimizes power consumption by combining N-type (electron conduction type) and P-type (hole conduction type) devices.
The researchers note that the Fermi level pinning phenomenon that occurs when graphene and metal are bonded is mitigated through the high-pressure hydrogen annealing process by controlling doping of the graphene channel in the form of NPN or PNP. This is the first implementation of a complementary ternary logic device that can be easily fabricated.
* Fermi level pinning phenomenon: Theoretically, when graphene and metal are bonded, the electrons move due to the difference in work function between graphene and metal, and the Fermi level of graphene changes. Due to the interface state of graphene and metal, the phenomenon of the Fermi level is fixed at a certain level
∘ So far, other researchers have reported ternary logic devices for only one N-type or P-type devices. In this study, the researchers have implemented N-type and P-type devices at the same time, and it is the first to suggest that the circuit could be implemented as a ternary logic device.
[Figure 3] Characteristics of strikeout logic device due to high-pressure hydrogen annealing. Electrical characteristics of graphene-based quadruple logic devices before high-pressure hydrogen annealing (left). Electrical characteristics of graphene-based striking logic devices after high pressure hydrogen heat treatment (right). After the high-pressure hydrogen annealing, the intermediate signal current (I1 ") is observed on the right. The above characteristic changes show the feasibility of implementing a complementary strip line logic device.
□ Professor Byoung Hun Lee said, "This achievement is significant for advancing the study of ternary logic devices by examining the concept of source devices required for the implementation of a graphene-based single-element ternary logic circuit capable of large area integration processes. This is expected to contribute to reducing the power consumption of core system technology required for the Internet of things, such as miniaturization of artificial intelligence system, which was difficult to put into practical use due to high power consumption."
□ This research was carried out with support of the Ministry of Science, ICT and Future Planning"s Nano and Source Material Technology Development Project, and it was published on December 19, 2017, in Scientific Reports.