Browsing by Author "Hsieh, JH"

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Advanced electrical imaging of dislocations in Mg-In-codoped GaN films
(2006-01-01)
Chen, SH
;
Hou, SP
;
Hsieh, JH
;
Chang, FC
;
Chen, WK
Conducting atomic force microscopy and scanning surface-potential microscopy have been applied to image the surfaces of Mg-In-codoped GaN films grown by low-pressure metal-organic chemical-vapor deposition. Biscyclopentadienylmagnesium (CP2Mg) and trimethylindium (TMIn) have been used as the codoping sources in the experiment. The dislocation density at the film surface reduces to the lowest level (similar to 1.0 X 10(9) cm(-2)) when the TMIn/CP2Mg flow rate ratio is about 1. The dislocation density tends to rise when the flow ratio increases, and carriers of the film accumulate near the rim of the dislocation at an accelerated speed. The work function of dislocation is also found lower than that of nondislocation areas. Such electrical unevenness may seriously influence the light emission of the component, which should not be ignored during fabrication and deserves careful attention. (c) 2006 American Vacuum Society.
Effect of magnesium on mechanical properties of Al2O3/Al-Zn-Mg-Cu metal matrix composites formed by squeeze casting
(1996-07-15)
Hsieh, JH
;
Chao, CG
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Al2O3Al-Zn-Mg-Cu composites containing 2.0-3.0wt% Mg in the matrix alloy have been fabricated by squeeze casting. Light microscopy, scanning electron microscopy and image analysis were used to examine and analyze the details of the microstructure and the fracture surface. Tensile tests were used to evaluate the mechanical properties. The aging behavior of the composites was studied using differential scanning calorimetry (DSC) techniques and microhardness tests. The microhardness and ultimate tensile strength (UTS) of the composites increase with increasing Mg content, The maximum microhardness and UTS of the composites occur after aging for 24 h at 120 degrees C.
Effect of magnesium on mechanical properties of Al2O3/Al-Zn-Mg-Cu metal matrix composites formed by squeeze casting
(1996-07-15)
Hsieh, JH
;
Chao, CG
;
交大名義發表
;
材料科學與工程學系
;
National Chiao Tung University
Al2O3Al-Zn-Mg-Cu composites containing 2.0-3.0wt% Mg in the matrix alloy have been fabricated by squeeze casting. Light microscopy, scanning electron microscopy and image analysis were used to examine and analyze the details of the microstructure and the fracture surface. Tensile tests were used to evaluate the mechanical properties. The aging behavior of the composites was studied using differential scanning calorimetry (DSC) techniques and microhardness tests. The microhardness and ultimate tensile strength (UTS) of the composites increase with increasing Mg content, The maximum microhardness and UTS of the composites occur after aging for 24 h at 120 degrees C.
Effect of magnesium on mechanical properties of Al2O3/Al-Zn-Mg-Cu metal matrix composites formed by squeeze casting
(1996-08-30)
Hsieh, JH
;
Chao, CG
;
交大名義發表
;
材料科學與工程學系
;
National Chiao Tung University
Al2O3/Al-Zn-Mg-Cu composites containing 2.0 similar to 3.0 wt.% Mg in the matrix alloy have been fabricated by squeeze casting. Light microscopy, scanning electron microscopy and image analysis were used to examine and analyze the details of microstructure and the fracture surface. Tensile tests were utilized to evaluate the mechanical properties. The aging behavior of the composites was studied by using differential scanning calorimetry technique and microhardness tests. The microhardness and ultimate tensile strength (UTS) of the composites increase with increasing Mg content. The maximum microhardness and UTS of the composites occur at 120 degrees C aging for 24 h.