Li Chaobo

In-Situ Nitrogen Doping of the TiO2 Photocatalyst Deposited by PEALD for Visible Light Activity

In this paper, an N-doped titanium oxide (TiO2) photocatalyst is deposited by a plasma-enhanced atomic layer deposition (PEALD) system through the in-situ doping method. X-ray photoelectron spectroscopy (XPS) analysis indicates that substitutional nitrogen atoms (~395.9 eV) with 1 atom% are effectively doped into TiO2 films. UV-VIS spectrometry shows that the in-situ nitrogen doping method indeed enhances the visible-activity of TiO2 films in the 425–550 nm range, and the results of the performance tests of the N-doped TiO2 films also imply that the photocatalysis activity is improved by in-situ doping. The in-situ doping mechanism of the N-doped TiO2 film is suggested according to the XPS results and the typical atomic layer deposition process.

Anodic bonding using a hybrid electrode with a two-step bonding process

A two-step bonding process using a novel hybrid electrode is presented. The effects of different electrodes on bonding time, bond strength and the bonded interface are analyzed. The anodic bonding is studied using a domestic bonding system, which carries out a detailed analysis of the integrity of the bonded interface and the bond strength measurement. With the aid of the hybrid electrode, a bubble-free anodic bonding process could be accomplished within 15-20 min, with a shear strength in excess of 10 MPa. These results show that the proposed method has a high degree of application value, including in most wafer-level MEMS packaging.

Influence of annealing temperature on passivation performance of thermal atomic layer deposition Al2O3 films

Chemical and field-effect passivation of atomic layer deposition (ALD) Al2O3 films are investigated, mainly by corona charging measurement. The interface structure and material properties are characterized by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), respectively. Passivation performance is improved remarkably by annealing at temperatures of 450 °C and 500 °C, while the improvement is quite weak at 600 °C, which can be attributed to the poor quality of chemical passivation. An increase of fixed negative charge density in the films during annealing can be explained by the Al2O3/Si interface structural change. The Al—OH groups play an important role in chemical passivation, and the Al—OH concentration in an as-deposited film subsequently determines the passivation quality of that film when it is annealed, to a certain degree.

Realization of conformal doping on multicrystalline silicon solar cells and black silicon solar cells by plasma immersion ion implantation

Emitted multi-crystalline silicon and black silicon solar cells are conformal doped by ion implantation using the plasma immersion ion implantation (PIII) technique. The non-uniformity of emitter doping is lower than 5%. The secondary ion mass spectrometer profile indicates that the PIII technique obtained 100-nm shallow emitter and the emitter depth could be impelled by furnace annealing to 220 nm and 330 nm at 850 °C with one and two hours, respectively. Furnace annealing at 850 °C could effectively electrically activate the dopants in the silicon. The efficiency of the black silicon solar cell is 14.84% higher than that of the mc-silicon solar cell due to more incident light being absorbed.

Large area graphene produced via the assistance of surface modification

We develop a novel and convenient method to prepare large area single-layer and multi-layer graphene through surface modification with oxygen plasma. The obtained large area single-layer graphene is dozens of microns wide in the lateral dimension and characterized by optical microscopy, atomic force microscopy. Raman spectroscopy show multilayer graphene has less disorder density than single-layer graphene. X-ray photoelectron spectroscopy (XPS) analysis shows that hydroxyl groups are formed on the HOPG surface during oxygen plasma pre-treatment. Hydrogen bonds develop between hydroxyl groups on HOPG surface and silanol groups on hydroxylated SiO2/Si substrate, which facilitate the transfer process. This study may provide a potential approach to develop graphene-based devices by using the large area lithographic printing process.

PEALD原位掺杂制备纳米TiO 2- x N x 光催化剂

采用等离子体增强型原子层沉积(PEALD)系统原位掺杂制备了TiO 2- x N x 光催化剂。利用光电子能谱(XPS)、高分辨率透射电镜(HRTEM)、光致发光(PL)光谱和紫外–可见光(UV-Vis)光谱对催化剂进行了表征, 并研究了TiO 2- x N x 纳米薄膜在可见光照射下水接触角的变化和催化降解亚甲基橙(MO)溶液的性能。结果表明, 等离子体功率变化可以改变掺入氮原子的结构, 在功率为50 W时主要形成替换式氮原子, 含量约为1.22at%, 晶体为锐钛矿(101)型。结构无明显缺陷, 且掺杂后TiO 2- x N x 薄膜光生电子–空穴对复合率低, 有利于光催化效率的提高。该方法解决了传统ALD工艺制备TiO 2- x N x 光催化剂时容易形成氧空位的问题, 实现了TiO2-xNx纳米材料的可见光( λ <800 nm)吸收和可见光光催化性能。采用等离子体增强型原子层沉积(PEALD)系统原位掺杂制备了TiO 2- x N x 光催化剂。利用光电子能谱(XPS)、高分辨率透射电镜(HRTEM)、光致发光(PL)光谱和紫外–可见光(UV-Vis)光谱对催化剂进行了表征, 并研究了TiO 2- x N x 纳米薄膜在可见光照射下水接触角的变化和催化降解亚甲基橙(MO)溶液的性能。结果表明, 等离子体功率变化可以改变掺入氮原子的结构, 在功率为50 W时主要形成替换式氮原子, 含量约为1.22at%, 晶体为锐钛矿(101)型。结构无明显缺陷, 且掺杂后TiO 2- x N x 薄膜光生电子–空穴对复合率低, 有利于光催化效率的提高。该方法解决了传统ALD工艺制备TiO 2- x N x 光催化剂时容易形成氧空位的问题, 实现了TiO2-xNx纳米材料的可见光( λ <800 nm)吸收和可见光光催化性能。