Three holes bound to a double acceptor - Be(+) in germanium

• Published in: Physical review letters Vol. 51; no. 12; pp. 1089 - 1091
• Main Authors: Haller, E. E., Mcmurray, R. E., Jr, Falicov, L. M., Haegel, N. M., Hansen, W. L.
• Format: Journal Article
• Language: English
• Published: Legacy CDMS American Physical Society 19-09-1983
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electronic transport in condensed matter; Exact sciences and technology; Photoconduction and photovoltaic effects; photodielectric effects; Physics; Solid-State Physics; Semiconductor materials; Impurity; Photoionization; Uniaxial stress; Infrared absorption; Impurity ionization; Germanium; Very low temperature; Shallow impurities; Experimental study; Photoconductivity
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.51.1089

A double acceptor binding three holes has been observed for the first time with photoconductive far-infrared spectroscopy in beryllium-doped germanium single crystals. This new center, Be(+), has a hole binding energy of about 5 meV and is only present when free holes are generated by ionization of either neutral shallow acceptors or neutral Be double acceptors. The Be(+) center thermally ionizes above 4 K. It disappears at a uniaxial stress higher than about a billion dyn/sq cm parallel to (111) as a result of the lifting of the valence-band degeneracy.