Diagnose to Cure: Identifying and Mitigating Performance-Limiting Defects in Two-Dimensional Transistors - College of Engineering - Purdue University

Project Description

Two-dimensional transition-metal dichalcogenides (TMDs) offer exceptional electrostatic scalability for future logic, yet their translation to advanced technology nodes remains limited by defects and variability whose physical origins are difficult to distinguish. A central challenge is that electrical signatures of defects are not uniquely attributable to their origin, making it difficult to determine which defects actually limit performance and therefore which should be targeted for mitigation.

This project will pursue a diagnose-to-cure strategy. The Fellow will combine purpose-built TMD-device architectures that selectively emphasize channel, dielectric, and interfacial defect populations with the development and application of light-based electrical measurements and spatially resolved scanning near-field spectroscopy. Together, these approaches will establish where electronically active defects reside, how they generate band-tail states, charge trapping, mobility degradation, threshold-voltage instability, and variability, and which populations dominate each failure mode. This mechanistic understanding will then guide targeted interventions—including dielectric and interface engineering, defect passivation, process modification, and device redesign which will be implemented in subsequent device generations and experimentally validated.

Co-advised by Thomas Beechem, Zhihong Chen and Joerg Appenzeller, the Fellow will connect fundamental defect physics to purposeful device fabrication and actionable strategies for next-generation TMD logic.

Start Date

Summer 2027

Postdoc Qualifications

Candidates should hold a Ph.D. in electrical engineering, mechanical engineering, materials science, applied physics, or a closely related field and possess a strong foundation in semiconductor device physics, nanoscale materials, or experimental condensed-matter physics. Particularly strong candidates will bring demonstrated expertise in one or more of the following: two-dimensional materials and transistors, semiconductor nanofabrication, electrical device characterization, optical or electro-optical spectroscopy, scanning near-field or scanning-probe techniques, dielectric/interface physics, or defect characterization.

The Fellow should be interested in using device design and advanced characterization together to solve mechanistic problems—developing experiments that distinguish competing defect populations, determining which defects control device behavior, and translating that understanding into materials, processing, and device-level solutions. Experience with electron-beam lithography, thin-film dielectrics, Raman or photoluminescence spectroscopy, near-field microscopy, automated electrical measurements, or quantitative data analysis is advantageous but not required. Candidates are not expected to enter with expertise in every area; the project is designed to develop integrated capabilities spanning device fabrication, semiconductor physics, and cutting-edge electro-optical characterization.

Co-advisors

Thomas Beechem, tbeechem@purdue.edu, ME/MSE, www.specere.org

Joerg Appenzeller, appenzeller@purdue.edu, ECE

Zhihong Chen, zhchen@purdue.edu, ECE

Bibliography

Y. Tan et al., “Monolayer WSe2 Field-Effect Transistor Performance Enhancement by Atomic Defect Engineering and Passivation,” ACS Nano, vol. 19, no. 9, pp. 8916–8925, Mar. 2025, doi: 10.1021/acsnano.4c16831.

S. Sharma et al., “Seed Layer Engineeringfor Effective Charge TransferDoping of MoS2 Transistors,” ACS Nano, vol. 20, no. 31, pp. 22033–22042, Aug. 2026, doi: 10.1021/acsnano.6c07322.

H.-Y. Lan et al., “Scaling two-dimensional semiconductor nanoribbons for high-performance electronics,” Nat Commun, vol. 17, no. 1, p. 7386, Jun. 2026, doi: 10.1038/s41467-026-74342-z.