This article reports a new attempt for the bandgap formation of cadmium sulfide nanocrystals (CdS NCs) synthesized on Si (111) substrates at low temperatures: 50 and 150 °C. The influence of energy gap alteration on the optoelectronic properties was extensively considered with the aid of various tools. A wurtzite-hexagonal structure in both CdS/Si NCs samples was confirmed by X-ray diffraction measurements. For a crystallite size around 7 nm, wider energy gaps (2.94 - 2.98 eV) were revealed by photoluminescence (PL) spectra. These values are in good conformity with the precise energy gaps: 2.95 eV and 3.04 eV that estimated using a reflection-electron energy loss spectroscopy. Consequently, such expansion in the energy bandgap indicates the occurrence of a blue shift compared to the bulk CdS. Moreover, the Raman spectra show three peaks referring to the first, second, and third-order scattering of the longitudinal optical phonon modes. The findings demonstrate the improved crystalline quality of the sample prepared at 150 °C with no need for further thermal annealing. It is thus inferred that quantum confinement is possible in the CdS NCs prepared at low temperatures using a pulsed-laser deposition technique; thereby, they are useful for optoelectronic applications.

本文报道了在低温（50和150°C）下在Si（111）衬底上合成的硫化镉纳米晶体（CdS NCs）带隙形成的新尝试。借助各种工具广泛地考虑了能隙变化对光电性能的影响。通过X射线衍射测量证实了两个CdS / Si NCs样品中的纤锌矿六方结构。对于约7 nm的微晶尺寸，通过光致发光（PL）光谱显示出更宽的能隙（2.94-2.98 eV）。这些值与精确的能隙高度吻合：使用反射电子能量损失光谱法估算的能隙为2.95 eV和3.04 eV。因此，这种能带隙的扩展表明与体CdS相比，发生了蓝移。此外，拉曼光谱显示了三个峰，分别涉及纵向光子声子模的一阶，二阶和三阶散射。这些发现证明了在150°C下制备的样品的结晶质量得到了改善，而无需进一步的热退火。因此可以推断，使用脉冲激光沉积技术在低温下制备的CdS NCs中可以进行量子限制。因此，它们可用于光电应用。