Phenomenological Model of Gate-Dependent Kink in I-V Characteristics of MoS<sub>2</sub> Double-Gate FETs
A phenomenological model, accounting for interface states at metal-semiconductor contacts, is proposed to explain particular gate-bias-dependent kinking in I-V characteristics sometimes observed in MoS<sub>2</sub> FETs. The effect is studied in double-gate FETs by varying top-gate voltag...
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| Format: | Article |
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IEEE
2021-01-01
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| Series: | IEEE Journal of the Electron Devices Society |
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| Online Access: | https://ieeexplore.ieee.org/document/9404298/ |
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| author | Michael A. Rodder Ananth Dodabalapur |
| author_facet | Michael A. Rodder Ananth Dodabalapur |
| author_sort | Michael A. Rodder |
| collection | DOAJ |
| description | A phenomenological model, accounting for interface states at metal-semiconductor contacts, is proposed to explain particular gate-bias-dependent kinking in I-V characteristics sometimes observed in MoS<sub>2</sub> FETs. The effect is studied in double-gate FETs by varying top-gate voltage (V<sub>TG</sub>) and bottom-gate voltage (V<sub>BG</sub>), with the MoS<sub>2</sub> semiconductor layer overlying source/drain (S/D) metal contacts in contact regions. The kink in I<sub>D</sub>-V<sub>TG</sub> characteristics is observed for small negative V<sub>BG</sub> but not for large negative V<sub>BG</sub>. The model divides the FET into S/D and channel regions, with bias-dependent S/D resistance (R<sub>SD</sub>) and channel resistance (R<sub>CHAN</sub>), and with S/D regions having an additional interface state distribution (additional to any interface states associated with semiconductor/dielectric interfaces in the channel region) due to an imperfect metal-semiconductor interface where MoS<sub>2</sub> overlies S/D metal. The additional interface states are modeled as a Gaussian distribution of acceptor-like states in the upper region of the semiconductor bandgap. When R<sub>SD</sub> ≥ R<sub>CHAN</sub> (V<sub>BG</sub> less negative), filling of these acceptor-like states as V<sub>TG</sub> increases creates a kink in I<sub>D</sub>-V<sub>TG</sub> characteristics since R<sub>SD</sub> is a major component of overall resistance limiting drain current, I<sub>D</sub>. Conversely, when R<sub>SD</sub> << R<sub>CHAN</sub> (V<sub>BG</sub> more negative), filling of these acceptor-like states as V<sub>TG</sub> increases does not create an I<sub>D</sub>-V<sub>TG</sub> kink since R<sub>SD</sub> is not the major component of resistance limiting I<sub>D</sub>. The model highlights 1) metal-semiconductor interface states need to be accounted for when modeling MoS<sub>2</sub> FETs, and 2) importance of forming metal-semiconductor interfaces with low interface state density to avoid I-V kinks which are detrimental for analog applications. |
| first_indexed | 2024-12-13T03:38:18Z |
| format | Article |
| id | doaj.art-c6ea226f3b3b4f449ae134ddf2d692c9 |
| institution | Directory Open Access Journal |
| issn | 2168-6734 |
| language | English |
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| series | IEEE Journal of the Electron Devices Society |
| spelling | doaj.art-c6ea226f3b3b4f449ae134ddf2d692c92022-12-22T00:00:59ZengIEEEIEEE Journal of the Electron Devices Society2168-67342021-01-01944144610.1109/JEDS.2021.30731299404298Phenomenological Model of Gate-Dependent Kink in I-V Characteristics of MoS<sub>2</sub> Double-Gate FETsMichael A. Rodder0https://orcid.org/0000-0002-7545-3165Ananth Dodabalapur1https://orcid.org/0000-0003-4327-8136Department of Electrical Engineering, University of Texas at Austin, Austin, TX, USADepartment Electrical and Computer Engineering, University of Texas at Austin, Austin, TX, USAA phenomenological model, accounting for interface states at metal-semiconductor contacts, is proposed to explain particular gate-bias-dependent kinking in I-V characteristics sometimes observed in MoS<sub>2</sub> FETs. The effect is studied in double-gate FETs by varying top-gate voltage (V<sub>TG</sub>) and bottom-gate voltage (V<sub>BG</sub>), with the MoS<sub>2</sub> semiconductor layer overlying source/drain (S/D) metal contacts in contact regions. The kink in I<sub>D</sub>-V<sub>TG</sub> characteristics is observed for small negative V<sub>BG</sub> but not for large negative V<sub>BG</sub>. The model divides the FET into S/D and channel regions, with bias-dependent S/D resistance (R<sub>SD</sub>) and channel resistance (R<sub>CHAN</sub>), and with S/D regions having an additional interface state distribution (additional to any interface states associated with semiconductor/dielectric interfaces in the channel region) due to an imperfect metal-semiconductor interface where MoS<sub>2</sub> overlies S/D metal. The additional interface states are modeled as a Gaussian distribution of acceptor-like states in the upper region of the semiconductor bandgap. When R<sub>SD</sub> ≥ R<sub>CHAN</sub> (V<sub>BG</sub> less negative), filling of these acceptor-like states as V<sub>TG</sub> increases creates a kink in I<sub>D</sub>-V<sub>TG</sub> characteristics since R<sub>SD</sub> is a major component of overall resistance limiting drain current, I<sub>D</sub>. Conversely, when R<sub>SD</sub> << R<sub>CHAN</sub> (V<sub>BG</sub> more negative), filling of these acceptor-like states as V<sub>TG</sub> increases does not create an I<sub>D</sub>-V<sub>TG</sub> kink since R<sub>SD</sub> is not the major component of resistance limiting I<sub>D</sub>. The model highlights 1) metal-semiconductor interface states need to be accounted for when modeling MoS<sub>2</sub> FETs, and 2) importance of forming metal-semiconductor interfaces with low interface state density to avoid I-V kinks which are detrimental for analog applications.https://ieeexplore.ieee.org/document/9404298/MoS₂double-gate FETI-V kinkinterface statesphenomenological model |
| spellingShingle | Michael A. Rodder Ananth Dodabalapur Phenomenological Model of Gate-Dependent Kink in I-V Characteristics of MoS<sub>2</sub> Double-Gate FETs IEEE Journal of the Electron Devices Society MoS₂ double-gate FET I-V kink interface states phenomenological model |
| title | Phenomenological Model of Gate-Dependent Kink in I-V Characteristics of MoS<sub>2</sub> Double-Gate FETs |
| title_full | Phenomenological Model of Gate-Dependent Kink in I-V Characteristics of MoS<sub>2</sub> Double-Gate FETs |
| title_fullStr | Phenomenological Model of Gate-Dependent Kink in I-V Characteristics of MoS<sub>2</sub> Double-Gate FETs |
| title_full_unstemmed | Phenomenological Model of Gate-Dependent Kink in I-V Characteristics of MoS<sub>2</sub> Double-Gate FETs |
| title_short | Phenomenological Model of Gate-Dependent Kink in I-V Characteristics of MoS<sub>2</sub> Double-Gate FETs |
| title_sort | phenomenological model of gate dependent kink in i v characteristics of mos sub 2 sub double gate fets |
| topic | MoS₂ double-gate FET I-V kink interface states phenomenological model |
| url | https://ieeexplore.ieee.org/document/9404298/ |
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