Thin hydrogenated amorphous silicon carbide layers with embedded Ge nanocrystals

The in-situ combination of plasma-enhanced chemical vapor deposition (PECVD) and vacuum evaporation in a vacuum chamber allowed us to integrate germanium nanocrystals (Ge NCs) into hydrogenated amorphous silicon carbide (a-SiC:H) thin films deposited from monomethyl silane diluted with hydrogen. Transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) spectroscopy were used for the microscopic characterization of the thin films, while photothermal deflection spectroscopy (PDS) and near-infrared photoluminescence spectroscopy (NIR PL) were used for their optical characterization. The presence of Ge NCs embedded in the amorphous a-Si:C:H was confirmed by TEM and EDX. The Ge NCs embedded in a-SiC:H layers in-creased optical absorption in the NIR spectral region. The quenching of a-SiC:H NIR PL due to the presence of Ge indicates that the diffusion length of free charge carriers in a-SiC:H is in the range 10-30 nm, an order of magnitude less than in a-Si:H. The optical properties of a-SiC:H films were degraded after vacuum annealing at 550 C.

在真空腔室内原位结合等离子体增强化学气相沉积（PECVD）与真空蒸发技术，使我们能够将锗纳米晶体（Ge NCs）集成到由氢气稀释的一甲基硅烷沉积而成的氢化非晶碳化硅（a-SiC:H）薄膜中。透射电子显微镜（TEM）和能量色散X射线（EDX）光谱被用于薄膜的微观表征，而光热偏转光谱（PDS）和近红外光致发光光谱（NIR PL）则用于其光学表征。TEM和EDX证实了嵌入非晶a-SiC:H中的Ge NCs的存在。嵌入a-SiC:H层中的Ge NCs增强了近红外光谱区域的光吸收。Ge的存在导致a-SiC:H的近红外光致发光（NIR PL）猝灭，这表明a-SiC:H中自由载流子的扩散长度在10-30 nm范围内，比a-Si:H中的扩散长度小一个数量级。在550℃真空退火后，a-SiC:H薄膜的光学性能出现退化。