Bias Temperature Stress Instability of Multilayered MoS2 Field-Effect Transistors With CYTOP Passivation

• Published in: IEEE transactions on electron devices Vol. 66; no. 5; pp. 2208 - 2213
• Main Authors: Seo, Seung Gi, Jin, Sung Hun
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-05-2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Bias; Bias temperature stress; cyclized transparent optical polymer (CYTOP) passivation; Effectiveness studies; Electron traps; Energy distribution; Field effect transistors; Fluoropolymers; High temperature; Hole traps; Molybdenum; Molybdenum disulfide; MoS₂ FETs; Passivation; Semiconductor devices; Stability; Stress; Sulfur; Temperature; Threshold voltage; trap energy distribution
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2019.2904338

Bias temperature stress instability on multilayered MoS 2 FETs was systematically investigated with the device scheme encapsulated with amorphous fluoropolymers [cyclized transparent optical polymer (CYTOP)] for the secure of minimization of external gas ambient effects. Large threshold voltage shifts (<inline-formula> <tex-math notation="LaTeX">\Delta {V}_{\textsf {th}} </tex-math></inline-formula>) for the negative bias temperature stress (NBTS) were observed, compared to the positive bias temperature stress (PBTS). Herein, the asymmetry behaviors on <inline-formula> <tex-math notation="LaTeX">\Delta {V}_{\textsf {th}} </tex-math></inline-formula>, observed in this paper, are ascribed to the sulfur vacancy in MoS 2 layers, leading to large hole traps compared to electron traps in MoS 2 layers. Moreover, high-temperature-sensitivity [<inline-formula> <tex-math notation="LaTeX">{d} </tex-math></inline-formula>(<inline-formula> <tex-math notation="LaTeX">\Delta {V}_{\textsf {th}} </tex-math></inline-formula>)/ dT ] on <inline-formula> <tex-math notation="LaTeX">\Delta {V}_{\textsf {th}} </tex-math></inline-formula> for PBTS than NBTS was observed, and their origins are possibly due to synergetic effects associated with large trap energy distribution (<inline-formula> <tex-math notation="LaTeX">{k}_{o}{T} </tex-math></inline-formula>) for electron trap levels.