From the above results, it is clear

that better crystallization of Si QDs in the ZnO matrix is required to decrease the absorption from a-Si QDs and thus efficiently reduce the optical loss in the long-λ range for better optoelectronic device performance. We find that a high-enough T ann for the Si QD-embedded ZnO thin film is critical to significantly improve the optical JQ1 price properties. Figure 3 Optical properties. Optical transmittance spectra of the Si QD-embedded ZnO thin films under different T ann. The images of the Si QD-embedded ZnO thin films after annealing are examined by SEM. The local film prominences are observed when T ann is higher than 600°C. Figure 4a shows the cross-sectional SEM image of a sample annealed at 700°C.

The local film prominence density and diameter in average are estimated and shown in Figure 4b. The prominence density increases almost linearly from 5.5 to 7.6 ones per 10 × 10 μm2 when increasing T ann from 600°C to 800°C with a close average diameter of BIBW2992 order about 2 μm. According to Raman spectra, the phase transformation of a- to nc-Si QDs happens when T ann is larger than 600°C, and f c also increases with increasing T ann from 600°C to 800°C. This strong correlation between f c and prominence density means that the volume variation from the phase transformation of a- to nc-Si QDs embedded in the ZnO matrix during annealing can produce an interior film stress and lead to the occurrence of local film

prominences. Figure 4 Thin film image. (a) Cross-sectional SEM image and (b) local film prominence density and diameter in average for the Si QD-embedded ZnO thin films Gefitinib after annealing. To understand the electrical properties of the Si QD-embedded ZnO thin films, the vertical resistivity (ρ) is calculated from the slope of the I-V curve under a high forward bias region of 4 ~ 5 V. When increasing T ann, the ρ can be reduced by the improved crystalline quality of Si QDs but also raised by the increased film prominence density and degraded crystalline quality of the ZnO matrix. Figure 5a shows the obtained ρ under different T ann, which slightly increases when increasing T ann from 500°C to 700°C but still keeps a low resistivity of approximately 104 Ω cm, significantly lower than that (approximately 108 Ω cm) of the intrinsic Si QDs embedded in a SiO2 matrix [17, 18]. It is evident that using ZnO as matrix can overcome the issue of highly resistive nature of the traditional Si-based dielectric matrix materials, and 104 times improvement of ρ is obtained. The ρ largely increases for the sample annealed at 800°C, which may have resulted from the excess film prominences produced during annealing since the film prominences will lead to local broken circuit regions at the interface of film/substrate and significantly increase the resistivity.