Doping of low-temperature GaAs and GaMnAs with carbon

• Published in: Applied physics letters 2004-11, Vol.85 (20), p.4678-4680
• Main Authors: Schott, G. M., Rüster, C., Brunner, K., Gould, C., Schmidt, G., Molenkamp, L. W., Sawicki, M., Jakiela, R., Barcz, A., Karczewski, G.
• Format: Article
• Language: English
• Subjects: CARBON; CURIE POINT; DOPED MATERIALS; FERROMAGNETIC MATERIALS; GALLIUM ARSENIDES; IMPURITIES; LATTICE PARAMETERS; LAYERS; MAGNETIZATION; MANGANESE ARSENIDES; MATERIALS SCIENCE; MOLECULAR BEAM EPITAXY; POINT DEFECTS; SEMICONDUCTOR MATERIALS; TEMPERATURE RANGE 0400-1000 K
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.1819522

The incorporation of carbon in low-temperature (LT) GaAs and GaMnAs layers deposited by molecular-beam epitaxy under various growth conditions has been investigated. The lattice parameter depends on Mn content, C content, and the growth conditions which strongly affect Mn, C , and point defect incorporation. We found optimum growth conditions ( T sub = 270 ° C , the beam equivalent pressure ratio is 5, growth rate is 0.1 nm ∕ s ) at which high-quality GaMnAs layers with moderate Mn content as well as LT-GaAs layers were deposited, which were efficiently p -doped by carbon. LT GaAs:C revealed the same electrical activation of carbon of about 50% at a high doping level p = 5 × 10 19 cm − 3 as observed in high-temperature GaAs:C. The Curie temperature as well as the saturation magnetization of GaMnAs decreases with C doping. This suggests a reduced amount of Mn contributing to the ferromagnetic phase in GaMnAs:C.