Abstract
B-doped hydrogenated amorphous silicon carbide (a-SiC:H) thin films were prepared by plasma-enhanced chemical-vapor deposition in a gas mixture of $SiH_4$, $CH_4$ and $B_2H_6$. Microstructures and chemical properties of a-SiC:H films grown with varing the volume ratio of $CH_4$ to $SiH_4$ were characterized with various analysis methods including scanning electron microscopy(SEM), X-ray diffractometry(XRD), Raman spectroscopy, Fourier-transform infrared (FTIR) spectroscopy. X-ray photoelectron spectroscopy(XPS), UV absorption spectroscopy and photoconductivity measurements. While Si:H films grown without $CH_4$ showed amorphous state, the addition of $CH_4$ during deposition enhanced the development of a microcrystalline phase. By introducing C atoms into the film, Si-Si and Si--$\textrm{H}_{n}$ bonds of a -Si:H films were gradually replaced by Si-C, C-C, and Si--$\textrm{C}_{n}\textrm{H}_{m}$ bonds. Consequently, the electrical resistivity and optical bandgap of a-SiC:H films were increased with the C concentration in the film.
$SiH_4$, $CH_4$, $B_2H_6$ 혼합기체를 이용하여 플라즈마 화학증착법으로 탄화실리콘 (a-SiC:H) 박막을 증착하였다. 증착중에 혼합기체중의$CH_4$농도 ($CH_4/CH_4+SiH_4$)를 변화시켜 얻은 박막의 물성을 SEM, XRD, Raman 분광법, FTIR, XPS, 광흡수도와 광전도도 분석을 통하여 살펴보았다. $SiH_4$기체만 이용하여 증착한 Si:H 박막은 비정질상태를 나타내었으나, $CH_4$가 첨가됨에 따라 실리콘 박막의 Si-$\textrm{H}_{n}$(n은 정수) 결합기가 Si-$\textrm{C}_{n}\textrm{H}_{m}$ (n,m은 정수) 형태의 결합기로 변화되었으며, 박막내 수소함량은 $CH_4$농도가 0~0.8의 범위에서 증가함에 따라 30~45% 범위에서 증가하였다. 반응기체중의 $CH_4$농도의 증가에 따라 박막 내의 탄소 농도가 증가함을 확인하였으며, 이에 따라 막의 전기비저항과 광학적밴드갭 역시 증가하였다.
