Cs. Son et al., ELECTRICAL-PROPERTIES OF HEAVILY CARBON-DOPED GAAS EPILAYERS GROWN BYATMOSPHERIC-PRESSURE METALORGANIC CHEMICAL-VAPOR-DEPOSITION USING CBR4, JPN J A P 1, 35(12B), 1996, pp. 6562-6565
Heavily carbon (C)-doped GaAs epilayers with hole concentrations as hi
gh as 3.1 x 10(20) cm(-3) were grown by atmospheric pressure metalorga
nic chemical vapor deposition using CBr4 as the dopant source. The ele
ctrical properties of C-doped GaAs epilayers simultaneously grown on e
xact and 2 degrees off (100) GaAs substrates were investigated. The ho
le concentration in the epilayer grown on the exact (100) substrate wa
s higher than that in the epilayer on the 2 degrees off (100) substrat
e grown under equivalent conditions. The hole concentration for the ex
act (100) substrates exhibited saturation as the growth temperature in
creased. The hole concentration for the 2 degrees off (100) substrates
exhibited thermal activation behavior. The activation energy of the h
ole concentration as a function of the growth temperature did not chan
ge significantly regardless of the V/III ratio (E(a) similar to 63 and
71 kcal/mol). The higher desorption rate of C-containing species due
to the higher adsorption rate of AsHx species on the 2 degrees off (10
0) substrate; which has a higher step density than the exact (100) sub
strate, is responsible for this thermal activation behavior.