C and Si delta doping in Ge by CH₃SiH₃ using reduced pressure chemical vapor deposition

C and Si delta doping in Ge are investigated using a reduced pressure chemical vapor deposition system to establish atomic-order controlled processes. CH₃SiH₃ is exposed at 250 °C to 500 °C to a Ge on Si (100) substrate using H₂ or N₂ carrier gas followed by a Ge cap layer deposition. At 350 °C, C and Si are uniformly adsorbed on the Ge surface and the incorporated C and Si form steep delta profiles below detection limit of SIMS measurement. By using N₂ as carrier gas, the incorporated C and Si doses in Ge are saturated at one mono-layer below 350 °C. At this temperature range, the incorporated C and Si doses are nearly the same, indicating CH₃SiH₃ is adsorbed on the Ge surface without decomposing the C−Si bond. On the other hand, by using H₂ as carrier gas, lower incorporated C is observed in comparison to Si. CH₃SiH₃ injected with H₂ carrier gas is adsorbed on Ge without decomposing the C−Si bond and the adsorbed C is reduced by dissociation of the C−Si bond during temperature ramp up to 550 °C. The adsorbed C is maintained on the Ge surface in N₂ at 550 °C. - Highlights: • C and Si delta doping in Ge is investigated using RPCVD system by CH₃SiH₃ exposure. • Atomically flat C and Si delta layers are fabricated at 350 °C. • Incorporated C and Si doses are saturated at one mono-layer below 350 °C. • CH₃SiH₃ adsorption occurred without decomposing C−Si bond. • Adsorbed C is desorbed due to dissociation by hydrogen during postannealing at 550 °C.