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We fabricated polycrystalline selenium (c-Se) based photodetectors using three different dielectrics (HfO2, Al2O3 and SiO2) as the hole blocking layer (HBL), and studied the influence of the HBLs on the photoconducting performance of the photodetectors. The microstructure of the c-Se layer is greatly influenced by the nucleation behavior of the tellurium (Te) adhesion layer deposited between the c-Se layer and the HBLs. The photoconducting performance of the photodetectors is basically dependent on the barrier height at the junctions of the HBL with the tin-doped indium oxide (ITO) anode and with the c-Se layer. A higher barrier height at the HBL/ITO junction leads to a lower dark current density (ID) of the photodetectors. However, the photodetector with the SiO2 HBL exhibits the largest ID as the bias exceeds 2 V although it has the highest junction barrier height. We attribute the abnormity to the rugged morphology of the c-Se layer, which is a result of a less dense Te nucleation on the SiO2 HBL. The photocurrent density (Iph) is inversely related to the junction barrier height at the HBL/c-Se contact. The c-Se photodetector with the HfO2 HBL has the largest IPh and the one with the SiO2 HBL has the smallest. The photodetector with the HfO2 HBL exhibits a quantum efficiency of ~ 89% at 6 V.

The random laser was investigated in gold-doped Zinc Oxide nanorods (Au-doped ZnO NRs) under a range of pumping power 0.25 - 4.66 mW. The Au-doped ZnO NRs prepared by chemical bath deposition (CBD) on the ZnO seed layer, were pre-coated on glass substrate using radio frequency magnetron sputtering (Rf-sputtering). The morphological of Au-doped ZnO NRs shows a hexagonal and strong vertically alignment against the substrate. The Energy dispersive spectroscopy (EDX) spectrum and elemental mapping results confirmed that Au atoms (at.%) are doped and spread over the ZnO NRs. More interestingly, the random laser of Au-doped ZnO shows a redshift of ~38 nm. This study showed the ability of using doping as a tuning parameter in the random laser, also provided an emphasis on Au-doped ZnO NRs as suitable options for controllable random laser devices.

Cracks easily generate in counterweight of forklift cast with high manganese pig iron which is by-product of smelters or low-grade manganese pig iron of Guangxi province of China. The causes of cracks formation and the solutions of cracks elimination are discussed. A large amount of carbides, phosphorus eutectic, inclusions, and arsenic element distribute on grain boundary of counterweight that causes crack. The measures to solve the cracks are as following: casting process would be improved, carbides and inclusions would be refined by adding rare earth, and arsenic would be eliminated by adding dearsenic catalyst which is composed of Ca-Fe alloy and the strong reducibility based additives. The distribution of phosphorus would be improved and phosphorus eutectic would be eliminated by adding 0.08%~0.15 %( wt %) Al or 1%~2 %( wt %) Mo.

In this investigation, a system-in-package (SiP) that consists of a very low-cost interposer with through-silicon holes (TSHs) and with chips on its top and bottom sides (a real 3-D IC integration) is studied. Emphasis is placed on the fabrication of a test vehicle to demonstrate the feasibility of this SiP technology. The design, materials, and process of the top chip, bottom chip, TSH interposer, and final assembly will be presented. Shock and thermal cycling tests will be performed to demonstrate the integrity of the SiP structure.

The lattice kinetic Monte Carlo simulation (kMCS) was applied to study the boron diffusion in Si-SiGe beyond nanotechnology. Both the interstitialcy and kick-out mechanisms of boron diffusion were considered, including the effects of annealing temperatures, boron dopant concentrations, Ge compositions, and concentrations of Si self-interstitial defects (SiI). The effects on boron diffusion caused by single and double layer(s) of SiGe phase with different Ge contents and varying boron concentrations in double layers of SiGe phase were also simulated. The results show that boron diffusion in Si and between SiGe-Si both largely increase as the temperature or concentration of SiI increases, but the boron diffusion between SiGe-Si is much less than in Si. Increasing the Ge contents in SiGe alloy could retard boron diffusion heavily, while increasing the boron concentration on SiGe phase would enhance boron diffusion.

A thermally reduced graphene oxide (TRGO) grown with carbon nanotubes composite (G-CNT) was utilized as three-dimensional highly conductive carbon scaffolds, where a large amount of small and homogeneous Pt nanoparticles (from 3.37 ± 1.22 to 4.24 ± 1.83 nm) was directly synthesized on G-CNT to acquire a new type of catalyst (Pt/G-CNT). Meanwhile, Pt nanoparticles loaded on TRGO (Pt/TRGO) and on TRGO blended with carbon nanotubes (Pt/G-b-CNT) were prepared for comparison. The G-CNT showed a very high electrical conductivity (144.4 S cm −1 ) compared to the G-b-CNT (67.5 S cm −1 ) and TRGO (9.1 S cm −1 ). In contrast to Pt/G-b-CNT (36.8 m 2 g −1 ) and Pt/TRGO (28.1 m 2 g −1 ), Pt/G-CNT showed a very high electrochemically active surface area (77.4 m 2 g −1 ). As these catalysts were utilized as the anode for the fuel cell, the maximum power density value for Pt/G-CNT (32.0 mW cm −2 ) was about 65% and 74% higher than that of Pt/G-b-CNT (19.4 mW cm −2 ) and Pt/TRGO (18.4 mW cm −2 ), respectively, and 26% higher than that of E-TEK (25.4 mW cm −2 ).

Monte Carlo technique is applied to simulate the synchronization between neighboring kinetic oscillators of nanoscaled supported platinum particles. Non-isothermal kinetics caused by local overheating provides an extra thermal conduction channel for synchronization between oscillators. Kinetic oscillation is produced when fast carbon monoxide oxidation is accompanied with slow subsurface oxygen formation and removal. Different effects are investigated on synchronization, including thermal conduction efficiency, heat dissipation efficiency, and distance between the two oscillators. Decreasing thermal conduction efficiency isolates each kinetically oscillating catalyst and results in complicated oscillation patterns. Heat dissipation has the opposite influence on synchronization comparing to thermal conduction. Low heat dissipation from the substrate to the environment maintains the temperature of the system and thus promotes synchronization. In addition, synchronization is destroyed when the distance between two oscillating particles becomes several-fold longer than the platinum particle size.

Theoretical calculation and simulation of FEM were proposed to explain the decline of change in resistance in Cu-Sn microbumps during the electromigration test. The IMC transformation from Cu 6 Sn 5 to Cu 3 Sn was supposed to be the reason. Being aware that the dimension keeps shrinking, the behavior for various solder diameters was also investigated.

In this study, we use the Cu/SnAg/Ni/Cu joint with a thickness of 7μm/8μm/2μm /5μm and 7μm/16μm/2μm /5μm. The diameter of the solder joint is about 30 μm and the UBM opening is 18 μm in diameter with 60 μm pitches. In order to measure the resistance changes, it was fabricated which constitute four probes. By using this method we can measure the resistance changes in microbump excluding the resistance changes in the wiring trace to make it more sensitive to subtle microstructure changes. We investigated the mechanisms of electromigration in microbumps with different stages when resistance increased 20%, 50% and 100% of the initial resistance. Solder joints were stressed with 0.56 A on 150°C hot plate. The average current density is 8 × 104 A/cm2, calculated based on the UBM opening. We ground the samples with 1000, 2000, and 4000 sand paper and then polished them with 1 μm, 0.3 μm, and 0.05 μm Al 2 O 3 We observed their morphologies with SEM and measured their component with EDX. In the bump with electron flow upward, we observed that microbumps were transformed into Cu 6 Sn 5 IMCs and Cu 3 Sn IMCs joints. In addition, voids were formed at the interface between nickel and solder. We found that both void formation and UBM dissolution were occurred. In the bump with electron flow downward, microbumps were transformed into IMC joints without void formation. To sum up, this study provides a better understanding on the relationship between the behavior of resistance curve and the morphology changes in microbumps.

In this investigation, a SiP (system-in-package) which consists of a very low-cost interposer with through-silicon holes (TSHs) and with chips on its top- and bottom-side (a real 3D IC integration) is studied. Emphasis is placed on the fabrication of a test vehicle to demonstrate the feasibility of this SiP technology. The design, materials, and process of the top-chip, bottom-chip, TSH interposer, and final assembly will be presented. Shock and thermal cycling tests will be preformed to demonstrate the integrity of the SiP structure.

Glass interposer is proposed as a superior alternative to organic and silicon-based interposers for 3DIC packaging in the near future. Because glass is an excellent dielectric material and could be fabricated with large size, it provides several attractive advantages such as excellent electrical isolation, better RF performance, better feasibility with CTE and most importantly low cost solution. In this paper, we investigated the EM performance of Cu RDL line with glass substrate. Three different physical properties of glass materials were used for studying the EM performance of Cu RDL line. The used testing conditions are under 150~170 °C and 300~500mA. The glass type material with best performance was applied for glass interposer process integration and assembly investigation. Therefore, a wafer-level 300mm glass interposer scheme with topside RDLs, Cu TGVs, bottom side RDLs, Cu/Sn micro-bump and PBO passivation has been successfully developed and demonstrated in the study. The chip stack modules with glass interposer were assembled to evaluate their electrical characteristics. Pre-conditioning test was performed on the chip stacking module with the glass interposer to assess the reliability of the heterogeneous 3D integration scheme. All the results indicate that the glass interposer with polymer passivation can be successfully integrated with lower cost processes and assembly has been successfully developed and demonstrated in the study.

In this work, the porous Pd/SiO2/GaN Schottky diode was fabricated by thermal evaporation (TE) for hydrogen sensing. The current-voltage (I-V) characteristics of the studied device were measured under hydrogen concentrations of 15 - 9970 ppm H2/air and temperatures of 303 - 515 K. Furthermore, the hydrogen sensing performances of this device were investigated via the steady-state and transient detections. From experimental results, the studied device demonstrated excellent sensing performances with low detection limit (about ppb level), wide detection range (15 -9970 ppm), high sensitivity, and fast response and recovery rates (within several seconds for detection of 9970 ppm H2/air). For the detection of 15 ppm at 423 K, the relative sensitivity even reached to 490%. In addition, the relative sensitivity was increased as either the hydrogen concentration or the detection temperature was incresaed. As compared with the dense structured device, the porous structured Pd/ SiO2/GaN Schottky diode exhibited more superior sensing characteristics, especially at low hydrogen concentration with a relatively high sensitivity.