LASER-ASSISTED CHEMICAL-VAPOR-DEPOSITION OF BORON

Ar+ laser-induced chemical vapor deposition (LCVD) of B from gaseous mixtures of BCl3 and H-2 has been investigated for temperatures between 1000 K and 2250 K and for partial pressure within the ranges 25 mbar less than or equal to p(BCl3) less than or equal to 800 mbar and 10 mbar I p(H,) less than or equal to 400 mbar. For the lowest temperatures, deposition is controlled by the chemical kinetics which, with p(BCl3) = p(H-2) = 100 mbar, is characterized by an apparent chemical activation energy of about 26.5 kcal/mol. In this regime, the deposited boron is amorphous. At high temperatures, deposition becomes limited by gas-phase transport and polycrystalline boron with beta-rhombohedral structure is obtained.