Browsing by Author "Liang, WD"

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Effect of different n-electrode patterns on optical characteristics of large-area p-side down InGaN light-emitting diodes fabricated by laser lift-off
(2005)
Chu, JT
;
Liang, WD
;
Kao, CC
;
Huang, HW
;
Chu, CF
Large-area (1000x1000 gm) p-side down InGaN light-emitting diodes (LEDs) have been fabricated by laser lift-off (LLO) technique. The p-side down LEDs with different geometric patterns of n-electrode were fabricated to investigate electrode pattern-dependent optical characteristics. Current crowding effect was first observed in in the p-side down InGaN LLO-LEDs. The LEDs with well designed n-electrode shows a uniform distribution of light-emitting pattern and higher out put power due to uniform current spreading and minimization of thermal effect. The output power saturation induced by current crowding in the LEDs with simplest geometric n-electrode was demonstrated. In absent of transparent contact layer for current spreading, the n-electrode pattern has remarkable influence on the current distribution and consequently the light output power of the large-area p-side down LEDs.
Effects of different n-electrode patterns on optical characteristics of large-area p-side-down InGaN light-emitting diodes fabricated by laser lift-off
(2005-11-01)
Chu, JT
;
Kao, CC
;
Huang, HW
;
Liang, WD
;
Chu, CF
Large-area p-side-down InGaN light-emitting diodes (LEDs) 1000 x 1000 mu m(2) in size have been fabricated by laser lift-off (LLO). The p-side-down LEDs with different geometric patterns of n-electrodes were fabricated to investigate electrode pattern-dependent optical characteristics. The current crowding effect was observed in the large-area p-side-down InGaN LLO-LEDs. A LED with a well-designed n-electrode pattern shows a uniform distribution of light emission and a higher output power due to uniform current spreading. The output power saturation induced by the current crowding effect was investigated. In the absence of a transparent contact layer for current spreading, the n-electrode pattern has a marked influence on the current distribution and the consequent light output power of the large-area p-side-down LEDs.
Fabrication of large-area GaN-based light-emitting diodes on Cu substrate
(2005-04-01)
Chu, JT
;
Huang, HW
;
Kao, CC
;
Liang, WD
;
Lai, FI
A large-area GaN-based light-emitting diode (LED) 1000 x 1000 mu m(2) in size with a p-side down configuration was fabricated using wafer bonding and laser lift-off (LLO) techniques. The thin GaN LED was transferred onto a copper substrate without p peeling or cracks. The large-area LEDs showed a uniform light-emission pattern over entire defined mesa area without a transparent contact layer on the p-type GaN. The operating current of the large-area LEDs can be driven up to 1000 mA with continuously increasing light output-power. The light output-power is 240 mW with a driving current of 1000 mA. Large-area emission and high current operation make the LLO-LEDs applicable to high-power LED applications.
InGaN self-assembled quantum dots grown by metal-organic chemical vapour deposition with growth interruption
(2006-03-28)
Yao, HH
;
Lu, TC
;
Huang, GS
;
Chen, CY
;
Liang, WD
Self-assembled InGaN quantum dots (QDs) were grown by metal-organic chemical vapour deposition with growth interruption at low V/III ratio and low growth temperature on sapphire substrates. The effects of the interruption time on the morphological and optical properties of InGaN QDs were studied. The results show that the growth interruption can modify the dimension and distribution of InGaN QDs, and cause the QD emission wavelength to blue shift with increasing interruption time. A density of InGaN QDs of about 4.5 x 10(10) cm(-2) with an average lateral size of 11.5 nm and an average height of 1.6 nm can be obtained by using a growth interruption time of 60 s.
Large emitting area GaN based light emitting diode fabricated on conducting copper substrates
(2004)
Chu, JT
;
Liang, WD
;
Chu, CF
;
Kuo, HC
;
Wang, SC
Optically pumped GaN-based vertical cavity surface emitting laser at room temperature
(2005)
Chu, JT
;
Liang, WD
;
Kao, CC
;
Huang, HW
;
Lu, TC
The optically pumped lasing action at 414 nm was obtained from a GaN-based VCSEL with an InGaN multiple quantum wells and two dielectric DBRs fabricated by laser lift-off. The threshold pumping energy is 270 nJ at room temperature conditions.
Room-temperature operation of optically pumped blue-violet GaN-based vertical-cavity surface-emitting lasers fabricated by laser lift-off
(2006-04-01)
Chu, JT
;
Lu, TC
;
Yao, HH
;
Kao, CC
;
Liang, WD
Room-temperature optically pumped GaN-based vertical-cavity surface- emitting lasers (VCSELs) were demonstrated by laser lift-off. A VCSEL was fabricated by combining a GaN-based cavity with two dielectric distributed Bragg reflectors: SiO2/TiO2 and SiO2/Ta2O5. The Q factor of the VCSEL is 518 indicating a good interfacial layer quality of the structure. The laser emits blue-violet wavelength light at 414 nm under optical pumping at room temperature with a threshold pumping energy of 270 nJ. The laser emission has a narrow linewidth of 0.25 nm and a degree of polarization of 70%. The laser emission patterns clearly indicate a vertical lasing action of the VCSEL.