Browsing by Author "Lu, CM"

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Low-threshold-current-density, long-wavelength, highly strained InGaAs laser grown by metalorganic chemical vapor deposition
(2005-10-01)
Chen, IL
;
Hsu, WC
;
Kuo, HC
;
Yu, HC
;
Sung, CP
A long-emission-wavelength laser with multiple InGaAs/GaAs quantum wells without a strain-compensated barrier was grown by metalorganic chemical vapor deposition (MOCVD). InGaAs quantum well (QW) broad-area laser diodes with an emission wavelength of up to 1214 nm were realized. A measured room-temperature threshold current density of only 173 A/cm(2) for a 2-mm-cavity device and a transparency current density of 66 A/cm(2) were obtained. The internal quantum efficiency and laser cavity loss were 67% and 6 cm(-1), respectively.
Microstructure evolution during electromigration in eutectic SnPb solder bumps
(2004-08-01)
Lu, CM
;
Shao, TL
;
Yang, CJ
;
Chen, C
;
材料科學與工程學系
A technique has been developed to facilitate analysis of the microstructural evolution of solder bumps after current stressing. Eutectic SnPb solders were connected to under-bump metallization (UBM) of Ti/Cr-Cu/Cu and pad metallization of Cu/Ni/Au. It was found that the Cu6Sn5 compounds on the cathode/chip side dissolved after the current stressing by 5 x 10(3) A/cm(2) at 150 degreesC for 218 h. However, on the anode/chip side, they were transformed into (NixCu1-x)(3)Sn-4 in the center region of the UBM, and they were converted into (Cu-y,Ni1-y)(6)Sn-5 on the periphery of the UBM. For both cathode/substrate and anode/substrate ends, (Cu-y,Ni1-y)(6)Sn-5 compounds were transformed into (Ni-x,Cu1-x)(3)Sn-4. In addition, the bumps failed at cathode/chip end due to serious damage of the UBM and the Al pad. A failure mechanism induced by electromigration is proposed in this paper.