Voon Chun Hong, Assoc. Prof. Dr.This page provides access to scholarly publications by UniMAP Faculty members and researchers.http://dspace.unimap.edu.my:80/xmlui/handle/123456789/392062024-03-29T12:07:22Z2024-03-29T12:07:22ZThe Impacts of Platinum Diffusion to the Reverse Recovery Lifetime of a High Power Diode DevicesC.M., ChehMohd Khairuddin, Md ArshadRuslinda, Abdul RahimC., IbauVoon, Chun HongRamzan, Mat AyubUda, Hashimhttp://dspace.unimap.edu.my:80/xmlui/handle/123456789/685132020-10-26T06:20:30Z2016-01-01T00:00:00ZThe Impacts of Platinum Diffusion to the Reverse Recovery Lifetime of a High Power Diode Devices
C.M., Cheh; Mohd Khairuddin, Md Arshad; Ruslinda, Abdul Rahim; C., Ibau; Voon, Chun Hong; Ramzan, Mat Ayub; Uda, Hashim
The reverse recovery lifetime of a diode is one the key parameter in power electronics market. To make a diode with fast switching speed, diodes are often doped with impurities such as gold and platinum to improve its lifetime. In this works, we present the reverse recovery lifetime improvement of a power rectifier diode through platinum diffusion in the intrinsic region in between P-N junction using Design of Experiment (DOE) approach. A commercial available power rectifier is used in this study. We factored in the temperature and thermal diffusion time during the platinum diffusion process in our DOE. From results, DOE 2 (with shorter thermal duration and high temperature for diffusion) is selected based on meeting requirement for forward voltage and reverse recovery specifications i.e. forward voltage at 1.8V and reverse recovery time at 27ns.
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2016-01-01T00:00:00ZEffect of temperature of oxalic acid on the fabrication of Porous anodic alumina from Al-Mn alloysMohd Nazree, Derman, Dr.Foo, Kai LoongKhairel Rafezi, Ahmad, Dr.Uda, Hashim, Prof. Dr.Voon, Chun Honghttp://dspace.unimap.edu.my:80/xmlui/handle/123456789/351932014-06-09T02:15:54Z2013-01-01T00:00:00ZEffect of temperature of oxalic acid on the fabrication of Porous anodic alumina from Al-Mn alloys
Mohd Nazree, Derman, Dr.; Foo, Kai Loong; Khairel Rafezi, Ahmad, Dr.; Uda, Hashim, Prof. Dr.; Voon, Chun Hong
The influence of temperature of oxalic acid on the formation of well-ordered porous anodic alumina on Al-0.5 wt% Mn alloys was studied. Porous anodic alumina has been produced on Al-0.5 wt% Mn substrate by single-step anodising at 50 V in 0.5 M oxalic acid at temperature ranged from 5°C to 25°C for 60 minutes. The steady-state current density increased accordingly with the temperature of oxalic acid. Hexagonal pore arrangement was formed on porous anodic alumina that was formed in oxalic acid of 5, 10 and 15°C while disordered porous anodic alumina was formed in oxalic acid of 20 and 25°C. The temperature of oxalic acid did not affect the pore diameter and interpore distance of porous anodic alumina. Both rate of increase of thickness and oxide mass increased steadily with increasing temperature of oxalic acid, but the current efficiency decreased as the temperature of oxalic acid increased due to enhanced oxide dissolution from pore wall.
Link to publisher's homepage at http://www.hindawi.com/
2013-01-01T00:00:00ZA simple one-step anodising method for the synthesis of ordered porous anodic aluminaVoon, Chun HongMohd Nazree, Derman, Dr.Uda, Hashim, Prof. Dr.Khairel Rafezi Ahmad, Dr.Ho, Li Ngeehttp://dspace.unimap.edu.my:80/xmlui/handle/123456789/348622014-05-29T07:03:47Z2014-01-01T00:00:00ZA simple one-step anodising method for the synthesis of ordered porous anodic alumina
Voon, Chun Hong; Mohd Nazree, Derman, Dr.; Uda, Hashim, Prof. Dr.; Khairel Rafezi Ahmad, Dr.; Ho, Li Ngee
Porous anodic alumina (PAA) has been produced on aluminium substrate by single-step anodising at 50 V in 0.3 M oxalic acid at 15°C for 60 min. The highly ordered pore and cell structure was achieved by subjecting the PAA to oxide dissolution treatment in a mixture of chromic and phosphoric acids. The nanostructure prior and post-oxide dissolution treatment was examined under scanning electron microscope. It was found that the oxide dissolution treatment improves the regularity of the cell and pore structure significantly. Uniform closely packed honeycomb structure of PAA is obtained. The uniformities of pore diameter and interpore distance are also enhanced. Compared to the PAA prior treatment, it was noticed that the pore diameter of the post-treatment PAA increases.
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2014-01-01T00:00:00ZEffect of electrolyte concentration on the growth of porous anodic aluminium oxide (AAO) on Al-Mn alloysVoon, Chun HongMohd Nazree, Derman, Dr.http://dspace.unimap.edu.my:80/xmlui/handle/123456789/325042014-03-11T05:11:33Z2012-12-01T00:00:00ZEffect of electrolyte concentration on the growth of porous anodic aluminium oxide (AAO) on Al-Mn alloys
Voon, Chun Hong; Mohd Nazree, Derman, Dr.
In this study, the effect concentration of electrolyte on pore nucleation process during anodizing was investigated. It was found that the concentration of oxalic acid influenced the morphologies and regularities of porous AAO formed on aluminum-manganese substrate. When the concentration of oxalic acid is 0.1 M, the porous AAO exhibited a disordered pores arrangement and no long range order was observed. However, when the concentration was increased to 0.3 M and 0.5 M, hexagonal pores arrangement and long range order were obtained. Although the hexagonal pore arrangement was still retained, further increasing the concentration of oxalic acid to 0.7 M render the long range order disappeared. The rate of increase of oxide mass of porous AAO increased with the concentration of oxalic acid.
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2012-12-01T00:00:00Z