Pedram Khakbaz PhD Publications

Biography Pedram Khakbaz was born in Arak, Iran. He received his Ph.D. degree in electronics engineering from the University of Udine, Italy, in 2022 where he studied the electronic transport in devices based on two-dimensional semiconductors. From Sep. 2016 to Sep. 2018, he was with the computational nano-electronics lab and finished his M.Sc. degree in nano and micro-electronics engineering at the University of Tehran, Iran. In June 2022, Pedram joined the Institute for Microelectronics as a postdoctoral researcher and his current research interests include ab initio modeling and quantum transport for the modelling of devices based on 2D semiconductor materials.

Achieving atomic-level control over both the channel and gate insulator is critical for scaling field-effect transistors beyond the sub-nanometer node. A notable breakthrough in this direction involves the systematic layer-by-layer oxidation of the two-dimensional semiconductor Bi₂SeO₂, which leads to the formation of an atomically thin gate dielectric, bismuth oxyselenite (Bi₂SeO₅). This oxidation process yields a single-crystalline, atomically flat, and nearly lattice-matched interface between the semiconductor and its native oxide. The resulting β-phase of Bi₂SeO₅ incorporates SeO₃ tetrahedra between intact Bi₂O₂ layers, maintaining structural integrity with the parent material.

To evaluate its suitability for device integration, the electronic and dielectric properties of Bi₂SeO₂ and its native oxides were examined. The Bi₂SeO₂/Bi₂SeO₅ system fulfills the preferred combination of a low effective mass semiconductor and a higher mass insulator. The high out-of-plane dielectric constant of the oxide allows thicker layers without sacrificing electrostatic control, while the large dielectric constant of the channel material supports enhanced mobility by effectively screening charged defects and phonons. However, high in-plane permittivity in both materials may increase drain-induced short-channel effects, necessitating careful architectural choices such as FinFET or gate-all-around designs. The thermal stability of β-Bi₂SeO₅ was evaluated using molecular dynamics simulations up to 450 K. The SeO₃ tetrahedra exhibited rotational dynamics yet preserved their coordination throughout, and all simulated structures relaxed back to the original geometry after optimization, as illustrated below.