Arif U. Alam
McMaster University
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Publication
Featured researches published by Arif U. Alam.
Journal of Micromechanics and Microengineering | 2014
Arif U. Alam; M. M. R. Howlader; M.J. Deen
For heterogeneous integration in many More-than-Moore applications, surface preparation is the key step to realizing well-bonded multiple substrates for electronics, photonics, fluidics and/or mechanical components without a degradation in performance. Therefore, it is critical to understand how various processing and environmental conditions affect their surface properties. In this paper, we investigate the effects of oxygen plasma and humidity on some key surface properties such as the water contact angle, roughness and hardness of three materials: silicon (Si), silicon dioxide (SiO2) and glass, and their impact on bondability. The low surface roughness, high surface reactivity and high hydrophilicity of Si, SiO2 and glass at lower activation times can result in better bondability. Although, the surface reactivity of plasma-ambient-humidity-treated Si and SiO2 is considerably reduced, their reduction of roughness and increase of hydrophilicity may enable good bonding at low temperature heating due to augmented hydroxyl groups. The decrease of hardness of Si and SiO2 with increased activation time is attributed to higher surface roughness and the formation of amorphous layers of Si. While contact angle and surface roughness results show a correlation with bondability, the role of hardness on bondability requires further investigation.
Talanta | 2016
Yiheng Qin; Arif U. Alam; Si Pan; M. M. R. Howlader; Raja Ghosh; P. Ravi Selvaganapathy; Yiliang Wu; M. Jamal Deen
Highly sensitive, easy-to-fabricate, and low-cost pH sensors with small dimensions are required to monitor human bodily fluids, drinking water quality and chemical/biological processes. In this study, a low-temperature, solution-based process is developed to prepare palladium/palladium oxide (Pd/PdO) thin films for pH sensing. A precursor solution for Pd is spin coated onto pre-cleaned glass substrates and annealed at low temperature to generate Pd and PdO. The percentages of PdO at the surface and in the bulk of the electrodes are correlated to their sensing performance, which was studied by using the X-ray photoelectron spectroscope. Large amounts of PdO introduced by prolonged annealing improve the electrodes sensitivity and long-term stability. Atomic force microscopy study showed that the low-temperature annealing results in a smooth electrode surface, which contributes to a fast response. Nano-voids at the electrode surfaces were observed by scanning electron microscope, indicating a reason for the long-term degradation of the pH sensitivity. Using the optimized annealing parameters of 200°C for 48 h, a linear pH response with sensitivity of 64.71±0.56 mV/pH is obtained for pH between 2 and 12. These electrodes show a response time shorter than 18 s, hysteresis less than 8 mV and stability over 60 days. High reproducibility in the sensing performance is achieved. This low-temperature solution-processed sensing electrode shows the potential for the development of pH sensing systems on flexible substrates over a large area at low cost without using vacuum equipment.
RSC Advances | 2016
Arif U. Alam; Yiheng Qin; M. M. R. Howlader; M. Jamal Deen
In this paper, a direct bonding technology for liquid crystal polymer (LCP) and glass is developed for the first time by using sequential plasma-activated bonding which is based on physical sputtering followed by the formation of chemically reactive surfaces. The sequential-plasma-activated surfaces of glass and LCP show high hydrophilicity with moderate roughness. The adhesion between the activated LCP and glass surfaces is governed by hydroxyl group-mediated interfacial Si–OH–C covalent bonds. The post-bonding anodic treatment increases the amount of interfacial oxides by generating more singly-bonded oxides on the glass surface. The post-bonding thermal treatment rearranges the plasma-induced reactive sites and improves the conformal contact between the LCP and glass. A high bonding strength of 6.3 MPa is obtained between the LCP and glass when both anodic and thermal treatments are used. This simple and low-temperature direct bonding process for LCP and glass provides insights for future bonding between polymers and thin glass films.
Journal of Materials Chemistry C | 2017
Yiheng Qin; Arif U. Alam; M. M. R. Howlader; Nan-Xing Hu; M. Jamal Deen
Inkjet printing is used to deposit palladium films with different morphologies and electrical properties using different precursor thermolysis atmospheres. First, the precursor is reductively decomposed into amine-stabilized palladium clusters. In air, oxygen assists the decomposition of the organoamine ligands for the palladium clusters. Small nanoparticles are formed and fused to smooth films. In nitrogen, the residual ligands facilitate the formation of sub-micron spherical aggregates. In low vacuum, a bilayer film containing a bottom layer with fused nanoparticles and a top layer with spherical aggregates is formed. Such morphology is caused by the competition between the film formation processes in air and in nitrogen. The electrical properties of the films are determined by the whole film for the smooth film and by the bottom layer for the bilayer film. The temperature coefficient of resistance of the films can be adjusted from 0.067% °C−1 to −0.189% °C−1 by tuning the amount of semiconductive palladium oxide in the conduction path. In addition, humid air increases the resistance drift of the films by forming surface-adsorbed hydroxyl groups and/or molecular water. This study highlights the importance of precursor thermolysis atmospheres on the morphology and electrical properties of inkjet-printed palladium/palladium oxide films.
2017 5th International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D) | 2017
Taufique Z. Redhwan; Arif U. Alam; Yaser M. Haddara; M. M. R. Howlader
We report direct bonding of liquid crystal polymer and copper film for electrochemical sensing for the first time. A peel strength of 683 g/cm was observed indicating strong adhesion. X-ray photoelectron and electrochemical impedance spectroscopies were used to characterize the sensing electrodes.
ECS Journal of Solid State Science and Technology | 2013
Arif U. Alam; M. M. R. Howlader; M.J. Deen
Advanced Functional Materials | 2016
Yiheng Qin; Arif U. Alam; M. M. R. Howlader; Nan-Xing Hu; M. Jamal Deen
Sensors and Actuators B-chemical | 2018
Arif U. Alam; Yiheng Qin; M. M. R. Howlader; Nan-Xing Hu; M. Jamal Deen
Physical Chemistry Chemical Physics | 2015
M. M. R. Howlader; Arif U. Alam; Rahul P. Sharma; M. Jamal Deen
Journal of Chemical Education | 2017
Hao Jin; Yiheng Qin; Si Pan; Arif U. Alam; Shurong Dong; Raja Ghosh; M. Jamal Deen