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

• 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 CSi bond.
• Adsorbed C is desorbed due to dissociation by hydrogen during postannealing at 550 °C.

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 CSi 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 CSi bond and the adsorbed C is reduced by dissociation of the CSi bond during temperature ramp up to 550 °C. The adsorbed C is maintained on the Ge surface in N2 at 550 °C.