金刚石线锯切割多晶硅片表面特性与酸刻蚀制绒问题

为解决金刚石切割多晶硅片与常规HF-HNO3-H2O混合酸湿法制绒技术不兼容的问题,对金刚石切割多晶硅片的表面特性和大幅度提高混合酸溶液中HF的比例进行了刻蚀制绒实验.结果表明,金刚石线切割多晶硅片表面存在约33%的光滑条带区域,其余为与砂浆切割硅片表面相近的粗糙崩坑区域;这些光滑区域使得金刚石切割多晶硅片表面光反射率比砂浆切割多晶硅片高3%~4%;而且光滑区域在富HNO3和富HF的HF-HNO3-H2O混合酸溶液中均较难于腐蚀,使其刻蚀制绒后反射率比砂浆切割多晶硅片低1%~2%,制绒后的金刚石切割多晶硅片反射率比制绒后的砂浆切割多晶硅片高4%~6%,不能满足太阳电池生产要求.富HNO3和富HF两种酸刻蚀体系,均不能解决金刚石切割多晶硅片的制绒问题.     

硼烯/石墨烯异质结缺陷态电子结构的第一性原理研究

采用密度泛函理论系统研究了硼烯-石墨烯异质结中缺陷态对体系电子结构特性的影响.发现缺陷态存在于石墨烯一侧时会破坏异质结结构;但缺陷态存在于硼烯一侧时异质结结构仍然会稳定存在,并且体系电子结构随缺陷态密度改变而发生明显变化:从无缺陷态时的金属特性变为多缺陷态时的半导体特性.常温下的分子动力学模拟进一步验证了相关体系的动力学稳定性.     

明胶基多孔碳球电极材料的制备及电化学性能研究

Gelatin-based porous carbon beads have been fabricated from gelatin micro-spheres by means of solidification, carbonization and chemical activation with KOH. The physical properties of gelatin-based porous carbon beads were studied by a t-plot method based on N₂ adsorption isotherms. The gelatin-based porous carbon beads activated at 800 ℃ exhibited the largest specific surface area and resulted in the highest capacitance. Carbon/carbon super-capacitors cells assembled with the electrode materials in 1.0 mol·L^-1 NEt₄BF₄ / acetonitrile electrolyte have also been studied. The electrochemical properties of gelatin-based porous carbon beads electrode were studied by using constant-current discharge tests. The results indicate that the gelatin-based porous carbon beads electrode is with good cycling stability and specific capacitance of 119.8 F·g^-1.     

Simulation and experimental study of a novel bifacial structure of silicon heterojunction solar cell for high efficiency and low cost

A novel structure of Ag grid/SiN_x/n~+-c-Si/n-c-Si/i-a-Si:H/p~+-a-Si:H/TCO/Ag grid was designed to increase the efficiency of bifacial amorphous/crystalline silicon-based solar cells and reduce the rear material consumption and production cost. The simulation results show that the new structure obtains higher efficiency compared with the typical bifacial amorphous/crystalline silicon-based solar cell because of an increase in the short-circuit current(J_(sc)), while retaining the advantages of a high open-circuit voltage, low temperature coefficient, and good weak-light performance. Moreover,real cells composed of the novel structure with dimensions of 75 mm × 75 mm were fabricated by a special fabrication recipe based on industrial processes. Without parameter optimization, the cell efficiency reached 21.1% with the J_(sc) of 41.7 mA/cm~2. In addition, the novel structure attained 28.55% potential conversion efficiency under an illumination of AM 1.5 G, 100 mW/cm~2. We conclude that the configuration of the Ag grid/SiN_x/n~+-c-Si/n-c-Si/i-a-Si:H/p~+-a-Si:H/TCO/Ag grid is a promising structure for high efficiency and low cost.     

金刚石线锯切割多晶硅片的气相刻蚀制绒研究

采用气相刻蚀制绒法研究金刚石线锯切割多晶硅片制绒.加热体积比1∶3、总体积400 mL的HF-HNO3酸混合溶液到90℃,使酸混合溶液受热产生气相,利用气相对金刚石线锯切割多晶硅片表面进行制绒.结果表明,制绒15 min之后,硅片表面的切割纹被完全去除;小腐蚀坑密布硅片表面,尺寸小于1μm,而传统湿法酸制绒所形成的腐蚀坑尺寸大于10μm.气相刻蚀后的金刚石线锯切割多晶硅片表面的微观粗糙度比传统酸混液制绒后的金刚石线锯切割多晶硅片表面的微观粗糙度高3倍多.气相制绒效果明显,并仅有12.11％的低反射率.     

B36团簇组装一维纳米线的密度泛函研究

采用密度泛函理论计算方法系统研究了B₃₆团簇组装一维纳米线的几何结构、电子结构及稳定性.发现两种不同构型的B₃₆团簇组装纳米线静态结构能量相同,且均为动力学稳定结构,但二者电子结构明显不同:分别呈现出半金属和小带隙半导体特征.对两类纳米线的H原子吸附显示:半金属纳米线转变为半导体,而半导体纳米线仍保持为半导体,但带隙明显增大.表明H原子吸附对于B₃₆团簇组装纳米线的电子结构具有明显的调控作用.     

金刚石线锯切割多晶硅片的气相制绒研究

采用气相制绒方法对金刚石切割多晶硅片进行表面制绒.2g硅加到HF-HNO3-H2O(400mL,体积比为6:3:1)的酸混合溶液中在室温下反应产生气相,利用气相对金刚石切割多晶硅片表面进行制绒研究.制绒4min时,硅片表面的切割纹被完全去除、大坑套小坑的蜂窝状蚀坑密布硅片表面,减反效果显著,反射率低至19.51%.气相制绒后的金刚石切割多晶硅片表面的微观粗糙度比传统酸混合溶液制绒后的高约20%.     

含双dppz配体的钌(Ⅱ)配合物与G-四联体的相互作用研究

应用紫外-可见吸收光谱、荧光光谱、热变性、圆二色谱等方法在K+溶液中研究了富含鸟嘌呤的G-四联体(AG3(T2AG3)3)与钌髤配合物[Ru(L)(dppz)2](PF6)4(L=5,5′-二(三正丁胺基甲基)-2,2′-联吡啶离子,dppz=二吡啶并[3,2-a∶2′,3′-c]吩嗪)的相互作用。紫外和荧光滴定实验表明,配合物与G-四联体之间存在较强的亲和力,拟合得到的结合常数可达107;从热变性实验可以看出,该配合物能够有效地稳定DNA的四螺旋结构。     

直拉单晶硅片“黑心”现象性质分析

对一种黑心片样品进行了分析.在确认黑心区为低少子寿命区的基础上,发现其电阻率明显偏高;发现黑心区经Secco刻蚀后,表面密布重叠圆形蚀坑,但与普通位错蚀坑有明显特征性区别;从其密度、形状与出现条件来看,它与电子半导体业中普遍报告的氧化堆垛层错(OSF)也不一致;进一步发现黑心区经Sirtle刻蚀后,表面呈现典型的大小明显不同的两种漩涡缺陷蚀坑,其密度明显低于上述Secco蚀坑.根据所得结果推测:黑心区主要密布一种性质上与普通位错相近,而所造成晶格畸变特征与范围不同于普通位错的晶格缺陷,它不属于已知的OSF微缺陷,而可能是一种由结晶生长过程中过饱和氧沉淀诱发形成的位错环;此外,黑心区还含有少量漩涡缺陷.