Electrical properties of heavily carbon-doped GaAs epilayers grown by atmospheric pressure metalorganic chemical vapor deposition using CBr4

Abstract

Heavily carbon (C)-doped GaAs epilayers with hole concentrations as high as 3.1 x 10(20) cm(-3) were grown by atmospheric pressure metalorganic chemical vapor deposition using CBr4 as the dopant source. The electrical properties of C-doped GaAs epilayers simultaneously grown on exact and 2 degrees off (100) GaAs substrates were investigated. The hole concentration in the epilayer grown on the exact (100) substrate was higher than that in the epilayer on the 2 degrees off (100) substrate grown under equivalent conditions. The hole concentration for the exact (100) substrates exhibited saturation as the growth temperature increased. The hole concentration for the 2 degrees off (100) substrates exhibited thermal activation behavior. The activation energy of the hole concentration as a function of the growth temperature did not change 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 (100) substrate; which has a higher step density than the exact (100) substrate, is responsible for this thermal activation behavior.