Jerry Yang

All Publications

• Understanding the Impact of Contact-Induced Strain on the Electrical Performance of Monolayer WS2 Transistors. Nano letters Hoang, L., Jaikissoon, M., Köroğlu, Ç., Zhang, Z., Bennett, R. K., Song, J. H., Yang, J. A., Ko, J. S., Brongersma, M. L., Saraswat, K. C., Pop, E., Mannix, A. J. 2024

  Abstract

  Two-dimensional (2D) electronics require low contact resistance (RC) to approach their fundamental limits. WS2 is a promising 2D semiconductor that is often paired with Ni contacts, but their operation is not well understood considering the nonideal alignment between the Ni work function and the WS2 conduction band. Here, we investigate the effects of contact size on nanoscale monolayer WS2 transistors and uncover that Ni contacts impart stress, which affects the WS2 device performance. The strain applied to the WS2 depends on contact size, where long (1 μm) contacts (RC ≈ 1.7 kΩ·μm) show a 78% reduction in RC compared to shorter (0.1 μm) contacts (RC ≈ 7.8 kΩ·μm). We also find that thermal annealing can relax the WS2 strain in long-contact devices, increasing RC to 8.5 kΩ·μm. These results reveal that thermo-mechanical phenomena can significantly influence 2D semiconductor-metal contacts, presenting opportunities to optimize device performance through nanofabrication and thermal budget.

  View details for DOI 10.1021/acs.nanolett.4c02616

  View details for PubMedID 39365938

• Biaxial Strain Transfer in Monolayer MoS2 and WSe2 Transistor Structures. ACS applied materials & interfaces Michail, A., Yang, J. A., Filintoglou, K., Balakeras, N., Nattoo, C. A., Bailey, C. S., Daus, A., Parthenios, J., Pop, E., Papagelis, K. 2024

  Abstract

  Monolayer transition metal dichalcogenides are intensely explored as active materials in 2D material-based devices due to their potential to overcome device size limitations, sub-nanometric thickness, and robust mechanical properties. Considering their large band gap sensitivity to mechanical strain, single-layered TMDs are well-suited for strain-engineered devices. While the impact of various types of mechanical strain on the properties of a variety of TMDs has been studied in the past, TMD-based devices have rarely been studied under mechanical deformations, with uniaxial strain being the most common one. Biaxial strain on the other hand, which is an important mode of deformation, remains scarcely studied as far as 2D material devices are concerned. Here, we study the strain transfer efficiency in MoS2- and WSe2-based flexible transistor structures under biaxial deformation. Utilizing Raman spectroscopy, we identify that strains as high as 0.55% can be efficiently and homogeneously transferred from the substrate to the material in the transistor channel. In particular, for the WSe2 transistors, we capture the strain dependence of the higher-order Raman modes and show that they are up to five times more sensitive compared to the first-order ones. Our work demonstrates Raman spectroscopy as a nondestructive probe for strain detection in 2D material-based flexible electronics and deepens our understanding of the strain transfer effects on 2D TMD devices.

  View details for DOI 10.1021/acsami.4c07216

  View details for PubMedID 39226175

• Biaxial Tensile Strain Enhances Electron Mobility of Monolayer Transition Metal Dichalcogenides. ACS nano Yang, J. A., Bennett, R. K., Hoang, L., Zhang, Z., Thompson, K. J., Michail, A., Parthenios, J., Papagelis, K., Mannix, A. J., Pop, E. 2024

  Abstract

  Strain engineering can modulate the properties of two-dimensional (2D) semiconductors for electronic and optoelectronic applications. Recent theory and experiments have found that uniaxial tensile strain can improve the electron mobility of monolayer MoS2, a 2D semiconductor, but the effects of biaxial strain on charge transport are not well characterized in 2D semiconductors. Here, we use biaxial tensile strain on flexible substrates to probe electron transport in monolayer WS2 and MoS2 transistors. This approach experimentally achieves 2* higher on-state current and mobility with 0.3% applied biaxial strain in WS2, the highest mobility improvement at the lowest strain reported to date. We also examine the mechanisms behind this improvement through density functional theory simulations, concluding that the enhancement is primarily due to reduced intervalley electron-phonon scattering. These results underscore the role of strain engineering in 2D semiconductors for flexible electronics, sensors, integrated circuits, and other optoelectronic applications.

  View details for DOI 10.1021/acsnano.3c08996

  View details for PubMedID 38921699

• "BARBED-WIRE BOUNDARIES": HIDDEN CURRICULUM, FIRST-GENERATION AND LOW-INCOME ENGINEERING STUDENTS AND INTERNSHIP ACQUISITION JOURNAL OF WOMEN AND MINORITIES IN SCIENCE AND ENGINEERING Yang, J. A., Towles, J. D., Sheppard, S. D., Atwood, S. A. 2024; 30 (5)

  View details for Web of Science ID 001223811700002

• Today's Grad Students, Tomorrow's Faculty LGBTQIA plus Graduate Student Experiences Navigating the Insider/Outsider Paradox in Engineering QUEERNESS AS DOING IN HIGHER EDUCATION Bakka, B., Jennings, M., Yang, J. A., Cisneros, J., Jourian, T. J., Miller, R. A., Duran, A. 2023: 142-156

  View details for Web of Science ID 000956844800013

• LGBTQ plus in ECE: Culture and (Non)Visibility IEEE TRANSACTIONS ON EDUCATION Yang, J. A., Sherard, M. K., Julien, C., Borrego, M. 2021; 64 (4): 345-352

  View details for DOI 10.1109/TE.2021.3057542

  View details for Web of Science ID 000711633100006

• Resistance and Community-Building in LGBTQ+ Engineering Students Journal of Women and Minorities in Science and Engineering Yang, J. A., Sherard, M. K., Julien, C., Borrego, M. 2021; 27 (4): 1-33

  View details for DOI 10.1615/JWomenMinorScienEng.2021035089

• Buckled beam mechanical memory using an asymmetric piezoresistor for readout JOURNAL OF MICROMECHANICS AND MICROENGINEERING Lin, J., Shuvra, P., Yang, J. A., McNamara, S., Walsh, K., Alphenaar, B. 2020; 30 (7)

  View details for DOI 10.1088/1361-6439/ab870c

  View details for Web of Science ID 000536077400001