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Comparison of Si delta-doping with homogenous doping in GaAs.

Vergleich von Si Delta-Dotierung mit homogener Dotierung in GaAs
: Köhler, K.; Ganser, P.; Maier, M.


Journal of Crystal Growth 127 (1993), S.720-723 : Abb.,Lit.
ISSN: 0022-0248
Fraunhofer IAF ()
electrical property; elektrische Eigenschaft; Epitaxie; epitaxy; III-V Halbleiter; III-V semiconductors

Homogeneous and Delta-doped GaAs:Si, has been grown by moleclar beam epitaxy at growth temperatures between 410 and 660 degree C. The doping density varied from 1x10high18 to 1.5x10high20 cmhigh-3 and from 1x10high12 to 7x10high13 cmhigh-2 for the homogeneously and Delta-doped GaAs, respectively. For homogeneous doping at 410 degree C, the maximum carrier concentration is 1.9x10high19 cmhigh-3, while at 660 degree C it is only 7.4x10high18 cmhigh-3. In contrast, for the Delta-doping the highest maximum sheet carrier concentration of 2.5x10high13 cmhigh-2 is found at a growth temperature of 660 degree C, whereas at a growth temperature of 410 degree C the maximum sheet carrier concentration is only 5x10high12 cmhigh-2. We attribute the increasing maximum sheet carrier concentration of the Delta-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 homog eneously doped atoms is similar, we have determined the width of the dopant distribution by comparing the results of our homogeneously and Delta-doped samples for a given growth temperature. The width of the Delta-doping distribution is found to increase both with growth temperature (480-660 degree C) and doping density. No concentration dependent doping width is found for the lowest growth temperature of 410 degree C. The results were confirmed by SIMS analysis.