Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, 1001 Ta-Hsueh Road, Hsinchu 30010, Taiwan.
Nanoscale Res Lett. 2013 Oct 23;8(1):439. doi: 10.1186/1556-276X-8-439.
A Si quantum dot (QD)-embedded ZnO thin film is successfully fabricated on a p-type Si substrate using a ZnO/Si multilayer structure. Its optical transmittance is largely improved when increasing the annealing temperature, owing to the phase transformation from amorphous to nanocrystalline Si QDs embedded in the ZnO matrix. The sample annealed at 700°C exhibits not only high optical transmittance in the long-wavelength range but also better electrical properties including low resistivity, small turn-on voltage, and high rectification ratio. By using ZnO as the QDs' matrix, the carrier transport is dominated by the multistep tunneling mechanism, the same as in a n-ZnO/p-Si heterojunction diode, which clearly differs from that using the traditional matrix materials. Hence, the carriers transport mainly in the ZnO matrix, not through the Si QDs. The unusual transport mechanism using ZnO as matrix promises the great potential for optoelectronic devices integrating Si QDs.
采用 ZnO/Si 多层结构，在 p 型 Si 衬底上成功制备了嵌入 Si 量子点（QD）的 ZnO 薄膜。随着退火温度的升高，薄膜的光学透过率大大提高，这归因于非晶态到纳米晶态 Si QD 嵌入 ZnO 基体的相转变。在 700°C 退火的样品不仅在长波长范围内具有高的光学透过率，而且具有更好的电学性能，包括低电阻率、小开启电压和高整流比。通过使用 ZnO 作为 QD 的基体，载流子输运主要由多步隧穿机制主导，这与 n-ZnO/p-Si 异质结二极管相同，与使用传统基体材料明显不同。因此，载流子主要在 ZnO 基体中传输，而不是通过 Si QD。使用 ZnO 作为基体的这种非典型输运机制有望为集成 Si QD 的光电设备带来巨大的潜力。
