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Scientific Bulletin. Physical and Mathematical Research

Abstract

One of the main trends of today's electronics is the decreasing the sizes of MOSFET up to nanometer scale. In this connection there are two main views to the perspective of scaling. According to one of them limit of scaling is reached at sizes 10 nm order, however according to second view, still there are opportunity to decrease transistor to more lower sizes. In accordance with second approach it is suggested to continue the size scaling by modification the transistor structure or by using the new materials, particularly one or two dimensional materials. One of such suggestions is the designing of MOSFET on the basis of two dimensional dichalcogenides of transition metals (DTM).

However, one of disadvantages of such devices can be circumstance that the top as well as the bottom of the transistor channel has borders with oxide layers. Upper oxide layer is gate oxide layer and bottom oxide layer is back oxide layer. Because of low heat conductivity of the oxides, this condition can lead to decreasing the heat flow from the channel, during flow of current, in comparison with bulk MOSFET that results in self-heating effect (SHE), which influence to characteristics of the transistor. Therefore it is interesting and important to consider self-heating effect in MOSFET based on two dimensional DTM. Two dimensional MoS2 is most considered DTM as channel in MOSFETs, therefore in this work the self heating effect is simulated in MOSFET based on two dimensional MoS2. SHE dependence on degree of covering the channel by gate oxide and on the thickness of back oxide of the transistor is considered.

transistor is considered. 2D simulation is carried out with using the Advanced TCAD Sentaurus. The parameters of 2D MoS2 is not included in data base of the used soft, therefore for simulation the characteristics of 2D MoS2 based MOSFET the parameters and methods suggested in literature was used. The channel of simulated transistor based on monolayer MoS2 with thickness 0.65 nm and length 90 nm. Aluminum gate has thickness 2 nm and length 30 nm. The thickness of SiO2 back oxide is varied between 50 and 1020 nm.

At simulation the electron effective mass is corrected by some factor for reaching the same dependence of quantum capacitance on DOS as in theoretical two dimensional case. The length of transistor and gate length is enough long, therefore in simulation for accounting the SHE the thermodynamic model was used. The simulation have performed on the base of the parameters used in calibration as well as on the basis of thermodynamic parameters of 2D MoS2.

From simulation study of 2D MoS2 based MOSFET of perspective of self heating it is observed that channel temperatures in this devices is lower with respect to SOI FinFET with approximately the same geometries. However channel temperatures in 2D MoS2 based MOSFET is very sensitive to modification of transistor structure.

First Page

29

Last Page

34

DOI

07.2

References

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