Comparing Thermal Durability and Effects of Annealing Temperature on Characteristics of Hydrogen-Doped ZnO, AZO, and GZO Thin Films

In this work, undoped, aluminum-, and gallium-doped ZnO thin films (ZnO-H, AZO-H, and GZO-H, respectively) deposited on soda-lime glass substrates by magnetron sputtering method in a gas mixture of hydrogen and argon are annealed at various temperatures in the range of 200–500°C in air to evaluate the durability of those films under annealing temperature. From photoluminescence spectra, formation of point defects, especially oxygen vacancies, when hydrogen diffuses out of the films at high annealing temperature is exhibited via a significant increase of visible emissions. We find out that carrier concentration and Hall mobility of AZO-H and ZnO-H films dramatically decrease, while those of GZO-H film are still stable as the annealing temperature increased from 200°C to 300°C. We proposed a model for interpreting the thermal durability of GZO-H film that, at an annealing temperature of 300°C, Ga3+ ions located at adjacent Zn sites can push hydrogen atoms, which are broken out of the antibonding sites which are perpendicular to the c -axis (AB┴), into bond center sites paralleled to the c -axis (BC//). The movement of hydrogen from AB┴ to BC// site also gives rise to the durability of electrical properties of GZO-H films at the high annealing temperature.

Static Recrystallization in Aluminum/Graphene Composites

The aim of this work was to analyze the recrystallization behavior of cold rolled Aluminum/graphene composites during annealing. The Aluminum/graphene composite was cold rolled firstly, and then annealed at different temperature (250°C, 300°C, 350°C, 400°C) and for various time (1 h, 2 h, 8 h, 32 h). Full recrystallization did not occur until the annealing temperature was above 300 °C. With annealing temperature increasing from 250 to 300°C, the hardness of the composites decreased from 49.6 to 27.6 HV. Grain growth were not observed at high annealing temperature and longer annealing time, which suggested that Graphene has strong pinning effect on the grain boundary of Aluminum.

Influence of Saline Buffers over the Stability of High-Annealed Gold Nanoparticles Formed on Coverslips for Biological and Chemosensing Applications

Herein, coverslips were used as solid supports for the synthesis of gold nanoparticles (AuNPs) in three steps: (i) detergent cleaning, (ii) evaporation of 4 nm gold film and (iii) exposure at high annealing temperature (550 °C) for 3 h. Such active gold nanostructured supports were investigated for their stability performances in aqueous saline buffers for new assessments of chemical sensing. Two model buffers, namely saline-sodium phosphate-EDTA buffer (SSPE) and phosphate buffer saline (PBS), that are often used in the construction of (bio)sensors, are selected for the optical and microscopic investigations of their influence over the stability of annealed AuNPs on coverslips when using a dropping procedure under dry and wet media working conditions. A study over five weeks monitoring the evolution of the localized surface plasmon resonance (LSPR) chemosensing of 1,2-bis-(4-pyridyl)-ethene (BPE) is discussed. It is concluded that the optimal sensing configuration is based on annealed AuNPs exposed to saline buffers under wet media conditions (overnight at 4 °C) and functionalized with BPE concentrations (10−3–10−11 M) with the highest LSPR spectra after two weeks.

Development of photodiode via the rapid melt growth (RMG) materials for energy conversion device

<span>Germanium (Ge) photodiodes were fabricated with the new RMG crucible materials that were established in this study. Results show that Ge large square patterns with size of 208 µm x 208 µm were unable to be achieved if ion implantation process was used in formation of photodiode. Delamination can be observed on all test samples during polycrystalline silicon (poly-Si) deposition at 620 ^oC. This result was in contrast to a previous intrinsic Ge test structure, where good formation of squares with size similar to that 208 µm x 208 µm had been successfully attained even with high annealing temperature above 938 ^oC. This indicates that doping through ion implantation has affected Ge film and caused delamination even at low temperature. However, good formations of Ge stripes were attained along with the ion implantation process in fabricating the photodiode. Results show that the sheet resistance of Ge stripe has significantly decreased compared to previous Ge resistors. The better resistance is due to the thicker (500 nm) Ge layer. In the case of Ge stripes with a p-i-n junction, only small fraction of test samples have shown a diode characteristic but with high leakage current. Results of I-V measurement show that a large fraction of test samples produced resistor characteristics. The high leakage current is believed due to the fact that the Ge films formed at this stage were polycrystalline in structure. Thus the grain size of Ge stripe has affected the performance. Slight changes on the I-V characteristic of single Ge can be observed when samples were tested under illumination. Therefore, it has potential to be used for future development of energy conversion device. </span>

Effect of Annealing on the Interface and Mechanical Properties of Cu-Al-Cu Laminated Composite Prepared with Cold Rolling

Cu-Al-Cu laminated composite was prepared with cold roll bonding process and annealing was carried out to study the phase evolution during the annealing process and its effect on the mechanical properties of the composite. The experimental results showed that after annealing the brittle intermetallics in the interface mainly includes Al4Cu9, AlCu and Al2Cu. With the increase of annealing temperature, the tensile strength of the composite decreases and the elongation shows a different variation which increases at the beginning and then decreases after a critical point. This phenomenon is related to the evolution of intermetallic compounds in the interface of the composite. It was also found that the crack source of the tensile sample is in the interface and delamination appeared at high annealing temperature (450 °C).

Reliability of 4H-SiC (0001) MOS Gate Oxide by NO Post-Oxide-Annealing

In this work, we investigated the oxide reliability of 4H-SiC (0001) MOS capacitors, the oxide was fabricated about 60 nm by thermal oxidation temperature at 1350°C, the oxides than annealed at different temperatures and times in diluted NO (10% in N2). The 4H-SiC MOS structure was analyzed by C-V and I-V measurement. Compared the J-E curves and Weibull distribution curves of charge-to-breakdown for fives samples under different annealing temperature and time, it shows that the high annealing temperature improves the electrical properties as the lifetime enhanced. The mode value of field-to-breakdown (EBD) for thermal oxides by post-oxide-annealing in NO for 30 min at 1350°C was 10.09 MV/cm, the charge-to-breakdown (QBD) of this sample was the highest in all samples, and the QBD value at 63.2% cumulative failure rate was 0.15 C/cm2. The QBD of the sample annealing at 1200°C for 120 min was 0.06 C/ cm2. The effects of NO annealing in high temperature enhance the lifetime of electrical properties and field-to-breakdown obviously. It can be demonstrated that the annealing temperature as high as 1300°C for 30 min can be used to accelerate TDDB of SiC MOS gate oxide.