M. Pristovsek et al., In situ investigation of GaAs (001) intrinsic carbon p-doping in metal-organic vapour phase epitaxy, J CRYST GR, 221, 2000, pp. 149-155
Intrinsic carbon doping of GaAs (001) during metal-organic vapour-phase epi
taxial (MOVPE) growth using low V/III ratios was investigated by in situ re
flectance anisotropy spectroscopy (RAS). The surface reconstruction during
growth changes from arsenic-rich (1 x 2)-CH3 at high V/III ratios to galliu
m-rich (1 x 4)-CH3 at very low V/III ratios. This change in reconstruction
corresponds to three different incorporation regimes. For growth at low V/I
II ratios ((1 x 4)-CH2) the hole concentration saturates at approximate to
4 x 10(19) cm(-3) and the surfaces are smooth. At intermediate V/III ratios
(transition between (1 x 4)-CH2 and (1 x 2)-CH3) the doping level decrease
s following a power law dependency and the surface becomes rather rough. At
very high V/III ratios ((1 x 2)-CH3) the surfaces become smooth again and
the doping saturates at a temperature-dependent background doping level. Fo
r the growth at very low V/III ratios a new methyl desorption/arsenic adsor
ption limited growth mechanism is proposed, characterized by a very high ca
rbon incorporation and smooth surfaces. (C) 2000 Elsevier Science B.V. All
rights reserved.