甚高频等离子增强CVD法制备微晶硅锗薄膜的研究

发布时间：2018-06-15 02:52

  本文选题：微晶硅锗薄膜 + 甚高频等离子体增强化学气相沉积　； 参考：《河北工业大学》2010年硕士论文

【摘要】：微晶硅锗薄膜作为窄带隙材料，具有吸收系数高、带隙可调的优点，是非常有前景的叠层太阳电池的底电池吸收层材料。但薄膜中锗的增加，使缺陷态增多，影响薄膜的光电性能，阻碍了其在太阳能电池中的实际应用。 本文分别以Si_2H_6和GeH_4及SiH_4和GeH_4两种气体组合为源气体，用甚高频等离子增强化学气相沉积（VHF-PECVD）制备硅锗薄膜，研究锗对薄膜性能的影响。与SiH_4和GeH_4制备的薄膜系列相比，Si_2H_6和GeH_4制备的薄膜中锗的融入速率相对较慢；同时Si_2H_6和GeH_4制备的硅锗薄膜随着锗烷浓度的增加薄膜结构始终保持一定的有序度。GeH_4与Si_2H_6生长的薄膜在保持一定晶化比例的前提下，光敏性相对较高。与SiH_4相比，Si_2H_6在与GeH_4组合生长微晶硅锗薄膜有一定的优势。 采用Si_2H_6和GeH_4作为源气体制备微晶硅锗薄膜，通过调节反应过程中衬底温度、气体总流量、等离子功率和压强等参数，对微晶硅锗薄膜进行优化。最终发现：随着衬底温度的增加，薄膜有序度增加；随气体总流量增加，薄膜的生长速率增加，晶化率逐渐减小；随着功率的增加材料的晶化率增加，但当功率超过一定值时，，正离子对薄膜表面的轰击增强，增加了缺陷生成的几率并引起光电特性的劣化；反应气压过大会造成薄膜趋于非晶化，反应气压太小，容易造成缺陷态增加，降低薄膜质量。 最终，在衬底温度为190℃，锗烷浓度为10%，辉光功率12W，压强为100Pa的条件下，制备出晶化率为42.7%，锗含量为20%，光敏性达到103量级以上的微晶硅锗薄膜。
[Abstract]:As a narrow band gap material, microcrystalline silicon germanium film has the advantages of high absorption coefficient and adjustable band gap. It is a promising material for bottom cell absorption of laminated solar cells. However, the increase of germanium in the film leads to the increase of the defect state, which affects the photoelectric performance of the film and hinders its practical application in solar cells. SiGe thin films were prepared by VHF plasma enhanced chemical vapor deposition (VHF-PECVD) using Si2H6 and GeHCO4 and SiHST4 and GeHST4 gas combinations as source gases, respectively. The effect of germanium on the properties of SiGe thin films was studied. The incorporation rate of germanium in the films prepared by SiS _ 2H _ 6 and GeH _ S _ 4 is relatively slow compared with the films prepared by SiHs _ 4 and GeH _ S _ 4. At the same time, Si2H6 and Gehs _ 4 Si-germanium thin films kept a certain degree of order with the increase of the concentration of germanium. The Guang Min properties of the films grown by Si _ 2H _ 6 and Si _ 2H _ 6 were relatively high under the condition of keeping a certain ratio of crystallization to that of Si _ 2H _ 6. Compared with SiH _ (4), SiS _ (2) H _ (6) has some advantages in microcrystalline SiGe thin films grown in combination with GeHs _ (4). Si2H6 and Gehst4 were used as source gases to prepare microcrystalline SiGe thin films. The microcrystalline SiGe thin films were optimized by adjusting the substrate temperature, gas flux, plasma power and pressure. It is found that with the increase of substrate temperature, the order of the film increases, the growth rate of the film increases with the increase of the total gas flow rate, the crystallization rate decreases gradually, and the crystallization rate increases with the increase of power, but when the power exceeds a certain value, The positive ion bombardment on the surface of the film increases the probability of the formation of defects and leads to the deterioration of the photoelectric properties. The reaction pressure is too high and the reaction pressure is too small to lead to the increase of the defect state and the decrease of the film quality. Finally, under the conditions of substrate temperature of 190 鈩

本文编号：2020270