Unintentional Source Incorporation in Plasma-Assisted Molecular Beam Epitaxy

概要

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Introduction of nitrogen gas induces inefficient Al beam termination when the shutter closes during molecular beam epitaxy. In spite of the closed shutter of the Al cell, the epitaxial layer contains Al at a concentration ($n_{\text{Al}}$) of over $10^{18}$ cm-3. This depends on the vapor pressures of N2 ($P_{\text{N$_{2}$}}$) and Al ($P_{\text{Al}}$) as $n_{\text{Al}} \propto P_{\text{N$_{2}$}}P_{\text{Al}}$. An analytical model considering gas phase scattering reproduce the dependences, suggesting that a large amount of N2 gas causes the scattering of residual Al atoms with an occasional collision resulting in the atoms directed toward the substrate. Possible impacts on the epitaxial layer, caused by the Al incorporation and related phenomena, are also discussed. The scattering of Al, and its getter effect on other elements especially O can cause further undesirable incorporation of impurities within the epitaxial layer.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2009-12-25