Emily Toph
Advisor: Prof. Eric Vogel

will propose a doctoral thesis entitled,

Interface-Engineered MBE of InSe: Early-Stage Growth Control and Hall Sensor Performance

On

Wednesday, April 29 at 11 a.m. (EDT)
Pettit Microelectronics Building Room 102B

and/or

Virtually via MS Teams or Zoom

https://teams.microsoft.com/meet/253152803479756?p=3APd10saNQuRogNWn9

Meeting ID: 253 152 803 479 756

Passcode: Nr2U7Wa9

Committee
            Prof. Eric Vogel – School of Materials Science and Engineering (advisor)
            Prof. Mark Losego– School of Materials Science and Engineering
            Prof. Faisal Alamgir – School of Materials Science and Engineering

            Prof. Alan Doolittle – School of Electrical and Computer Engineering
            Dr. Brent Wagner – Georgia Tech Research Institute

Abstract
               This work aims to enable high-sensitivity, BEOL-compatible InSe Hall sensors by clarifying how the very first layers of film growth set the ultimate limits on mobility and noise. Although indium monoselenide (InSe) offers high intrinsic mobility, a layered van der Waals structure, and a suitable bandgap, MBE-grown films typically underperform exfoliated crystals because defects and competing phases are “baked in” during the first one to three monolayers at the substrate.

               To address this challenge, interface-engineered MBE is used to deliberately shape nucleation and early-stage growth. Metal-precursor layers, chalcogen pretreatments, and time-structured flux schemes are tuned to control nucleation density, phase stability, and grain coalescence, with the goal of producing phase-pure, continuous, low-roughness InSe films within BEOL thermal budgets. Structural and morphological characterization (Raman phase fraction analysis, AFM, TEM) is used to map how these interface-engineering strategies change phase composition, grain size, and interface disorder.

               The influence of substrate bonding and symmetry is further examined by applying these interface-engineered approaches across van der Waals, ionic, and covalent or amorphous platforms. Hall bar devices then relate interface and microstructural metrics directly to Hall mobility, carrier density, sheet resistance, and Hall sensitivity. By combining targeted interface control with quantitative electrical measurements, this thesis seeks to narrow the mobility gap between deposited and exfoliated InSe and to provide actionable guidelines for integrating InSe Hall sensors in future monolithic 3D electronics.