VERY HIGH-SILICON CONCENTRATION BY MOVPE IN GAAS

Epitaxial silicon-doped GaAs layers are grown by atmospheric pressure metalorganic vapour phase epitaxy (AP-MOVPE) using silane (SiH4) 500 p pm diluted in H-2 as a dopant source gas. The grown layers are charact erised by the van der Pauw method, secondary ion mass spectroscopy, ro om and low temperature photoluminescence experiments. The carrier conc entration has a growth temperature dependence when the SiH4 partial pr essure is lower than 6.7 x 10(-2) Pa. However, it has no temperature d ependence for SiH4 partial pressure higher than 6.7 x 10(-2) Pa and th e activation energy of Si incorporation varies from 0 to 2.2 eV. The c arrier concentration of Si-doped GaAs is usually saturated at 6 x 10(1 8) cm(-3) level. However, in this study a carrier concentration of up to 1 x 10(19) cm(-3) was obtained, which in our knowledge is the highe st carrier concentration ever reported for Si-doped GaAs by AP-MOVPE. Compensation ratios are firstly calculated from theoretical Hall mobil ity. Using room temperature photoluminescence data, theoretical fits o f the photoluminescence peaks, these compensation ratios are also dete rmined and they are compared with values obtained from mobility data.