Sun Xiao-jing, Ma Shu-yi, Wei Jin-jun, Xu Xiao-li
College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2008 Sep;28(9):2033-7.
Ge thin films were deposited on porous silicon substrate using the RF magnetron sputtering technique with Ge target and sputtering for 4, 8 and 12 min respectively. Ge-containing silicon oxide thin films were deposited on n-type Si substrate using the RF magnetron sputtering technique with a Ge-SiO2 composite uarget and with Ge wafer in the target having percentage areas of 5%, 15% and 30%, respectively. These samples were annealed in a N2 atmosphere at 300 degrees C, 600 degrees C and 900 degrees C for 30 min. A comparative study of photoluminescence from Ge/PS and Ge/SiO2 thin films is reported. The FTIR was used to research the structure of Ge/PS thin films. The FTIR showed that the Si-Hx (x = 1-3) absorption peaks disappeared, but Si-O-Si, Si2O-SiH and H2Si-O2 absorption peaks were enhanced, and the surfaces of Ge/PS thin films have formed a goodish integrated cross-linked Si-O-Si network. It was indicated that Ge thin films deposited on porous silicon can improve the level of oxidation. At the same time, the Si-O and Si-Si bonds on the surface of PS thin films were broken, but some new bands such as Si-Ge, Ge-Ge and Ge-O formed. As the results of the experiment showed that the photoluminescence peaks of Ge/PS thin films were located at 517 nm, the sputtering time influenced the intensity of light-emission remarkably and with increasing the thickness of Ge layer coated, the intensity of light-emission dropped abruptly. When Ge sputtered for 12 min, the photolumines cence peak almost disappeared. The photoluminescence peaks of Ge/SiO2 thin films were located at 580 nm, the percentage areas of Ge wafer in the target influenced the intensity of light-emission obviously, and with increasing the percentage area of Ge wafer in the sputtering target, the photoluminescence intensity was reduced greatly. Though with increasing the annealing temperature of different thin films, all the photolu minescence spectra from Ge/PS and Ge/SiO2 thin films changed scarcely, and our explanation is that Ge-related defects at the interfaces between PS and the Ge nanocrystals embedded in the pores were responsible for the photoluminescence of Ge/PS thin films. However, the photoluminescence of Ge/SiO2 thin films' light emission originates from luminescence centers in Si oxide films. Ge/PS and Ge/SiO2 thin films both contained Ge nanocrystals and silicon oxide layer, and have similar structure, however, they have different mechanism behind photoluminescence. The experimental results have been explained reasonably.
采用射频磁控溅射技术，以锗靶分别溅射4分钟、8分钟和12分钟，在多孔硅衬底上沉积锗薄膜。采用射频磁控溅射技术，以锗 - 二氧化硅复合靶，且靶中锗片的面积百分比分别为5%、15%和30%，在n型硅衬底上沉积含锗的氧化硅薄膜。这些样品在氮气气氛中于300℃、600℃和900℃退火30分钟。报道了对锗/多孔硅和锗/二氧化硅薄膜光致发光的对比研究。利用傅里叶变换红外光谱（FTIR）研究锗/多孔硅薄膜的结构。FTIR表明，Si - Hx（x = 1 - 3）吸收峰消失，但Si - O - Si、Si2O - SiH和H2Si - O2吸收峰增强，锗/多孔硅薄膜表面形成了较好的整体交联Si - O - Si网络。结果表明，沉积在多孔硅上的锗薄膜可提高氧化程度。同时，多孔硅薄膜表面的Si - O键和Si - Si键断裂，但形成了一些新的谱带，如Si - Ge、Ge - Ge和Ge - O。实验结果表明，锗/多孔硅薄膜的光致发光峰位于517nm处，溅射时间对发光强度有显著影响，随着锗层镀膜厚度的增加，发光强度急剧下降。当锗溅射12分钟时，光致发光峰几乎消失。锗/二氧化硅薄膜的光致发光峰位于580nm处，靶中锗片的面积百分比对发光强度有明显影响，随着溅射靶中锗片面积百分比的增加，光致发光强度大幅降低。尽管随着不同薄膜退火温度的升高，锗/多孔硅和锗/二氧化硅薄膜的所有光致发光光谱变化不大，我们的解释是，多孔硅与嵌入孔中的锗纳米晶体界面处的锗相关缺陷是锗/多孔硅薄膜光致发光的原因。然而，锗/二氧化硅薄膜的光致发光源于氧化硅薄膜中的发光中心。锗/多孔硅和锗/二氧化硅薄膜都含有锗纳米晶体和氧化硅层，且结构相似，然而，它们光致发光背后的机制不同。实验结果得到了合理的解释。
