Si_(1-y)C_y合金薄膜中替位式C组分随生长温度的变化

Variance of Substitutional C Fraction in Si_(1-y)C_y alloy Films with the Growth Temperature

用化学气相淀积方法,以乙烯为碳源、硅烷为硅源,在Si(100)衬底上外延生长了替位式C组分达1.22%的Si1-yCy合金薄膜,研究表明:处于替位式格点位置的C原子与Si原子成键,形成Si-C局域振动模;随着生长温度的降低,更多具有较低迁移率的C原子占据替位式格点,导致合金薄膜中的替位式C组分增加、间隙式缺陷减少,薄膜的晶体质量得到有效提高;相应地薄膜承受的张应力增大,外延层中Si(TO)声子模发生蓝移。

Si1-yCy alloy films,with the highest substitutional C fraction of 1.12%,were epitaxially deposited on Si(100) substrates via chemical vapor deposition(CVD) process,using C2H4 and SiH4 as C and Si resources,respectively.The results showed that incorporated C atoms occupying substitutional sites bind to Si atoms,and form Si-C local vibration mode(LVM).With the decrease of the growth temperature,more C atoms with lower mobility will be frozen onto substitutional sites,leading to the increase of substitutional C fraction.Accordingly,the film crystal quality improves effectively,due to the reduction of interstitial defects,and the tensile stress in epitaxial films becomes strengthened,with the blueshift of Si(TO) phonon mode.