Electron Enhanced Atomic Layer Deposition (Ee-Ald) for Room Temperature Growth of Gallium Nitride, Silicon, and Boron Nitride Films

Sprenger, Jaclyn Kelly

Graduate Thesis Or Dissertation

Electron Enhanced Atomic Layer Deposition (Ee-Ald) for Room Temperature Growth of Gallium Nitride, Silicon, and Boron Nitride Films Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/r207tp51m

Abstract

Electron enhanced atomic layer deposition (EE-ALD) can drastically reduce the temperatures required for film growth through electron stimulated desorption (ESD) of surface species. The desorption process creates highly reactive “dangling bond” surface sites. Precursors can then adsorb efficiently on the dangling bonds. EE-ALD enables deposition of thin films on thermally sensitive substrates and growth of laminate materials where alloying would occur at traditional processing temperatures. We have demonstrated the EE-ALD of polycrystalline GaN, BN, and amorphous Si at room temperature (27˚C). Film growth was performed using alternating exposures of the appropriate precursors and low energy electrons (~100 eV). X-ray reflectivity and spectroscopic ellipsometry measurements monitored linear film growth versus number of reaction cycles. Additionally, we observed some dependence of the growth rate on electron flux and electron energy. Growth rates varied from 0.2 Å/cycle for Si films to 3.2 Å/cycle for BN films. Depth-profiling using x-ray photoelectron spectroscopy demonstrated clean BN (1.3:1) films with < 3 at.% C and O impurities. Crystallites as large as 10 nm were observed by high-resolution transmission electron microscopy and grazing angle x-ray diffraction for GaN films. EE-ALD should facilitate the deposition of a variety of ALD films at low temperature. Materials grown with hydride or halide precursors are all possible candidates due to their large ESD cross-sections.

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