Comparison of Si δ-doping with homogeneous doping in GaAs
1993; Elsevier BV; Volume: 127; Issue: 1-4 Linguagem: Inglês
10.1016/0022-0248(93)90719-d
ISSN1873-5002
AutoresK. Köhler, P. Ganser, Matthias Maier,
Tópico(s)Semiconductor Quantum Structures and Devices
ResumoHomogeneous and δ-doped GaAs: Si, has been grown by molecular beam epitaxy at growth temperatures between 410 and 660°C. The doping density varied from 1×1018 to 1.5×1020 cm-3 and from 1×1012 to 7×1013 cm-2 for the homogeneously and δ-doped GaAs, respectively. For homogeneous doping at 410°C, the maximum carrier concentration is 1.9×1019 cm-3, while at 660°C it is only 7.4×1018 cm-3. In contrast, for the δ-doping the highest maximum sheet carrier concentration of 2.5×1013 cm-2 is found at a growth temperature of 660°C, whereas at a growth temperature of 410°C the maximum sheet carrier concentration is only 5×1012 cm-2. We attribute the increasing maximum sheet carrier concentration of the δ-doped samples with growth temperature to the increasing width of the doping spike due to segregation of the Si-atoms in GaAs. Assuming that the incorporation of the segregated atoms and the homogeneously doped atoms is similar, we have determined the width of the dopant distribution by comparing the results of our homogeneously and δ-doped samples for a given growth temperature. The width of the δ-doping distribution is found to increase both with growth temperature (480–660°C) and doping density. No concentration dependent doping width is found for the lowest growth temperature of 410°C. The results were confirmed by SIMS analysis.
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