Relationship between impurity (B or P) and carrier concentration in SiGe(C) epitaxial film produced by thermal treatment

Relationship between impurity (B or P) and carrier concentration in Si _1-x-y Ge _x C _y epitaxial films (0.22≤x≤0.7, 0≤y≤0.02) produced by thermal treatment has been investigated. In the case of the B-doped Si _1-x Ge _x films with B concentration of 10 ²¹ cm ^-3 , the carrier concentration slightly decreases with increasing temperature up to 800°C. Because the lattice constant of the film becomes larger with heat treatment, it is suggested that B clustering proceeds with heat treatment, in other words, the epitaxial film is grown in a non-equilibrium for B. In the case of the P-doped Si _1-x Ge _x films with P concentration of 10 ²⁰ cm ^-3 , the carrier concentration scarcely changes with heat treatment for lower Ge fraction (x≤0.44). For higher Ge fraction (x = 0.7), the carrier concentration becomes two times higher than that of as-deposited film after heat treatment at 800°C. Because the lattice constant of the film becomes smaller with heat treatment, it is suggested that the solid solubility of electrically active P atoms becomes higher due to the generation of substitutional P atoms at higher temperature. In the P-doped Si _0.54 Ge _0.44 C _0.02 film, it is considered that the generation of substitutional P atoms is enhanced by the localization of C atoms into the interstitial site due to heat treatment.