WANG Xiao-li, NIU Ping-juan, LI Xiao-yun, YU Li-yuan, YANG Guang-hua, LIU Hong-wei, GAO Tie-cheng, LUO Hu-ying, ZHAN Ying, YU Xin. The Study of High-brightness and High-power InGaAlP Red LED[J]. Chinese Journal of Luminescence, 2008,29(2): 330-336
WANG Xiao-li, NIU Ping-juan, LI Xiao-yun, YU Li-yuan, YANG Guang-hua, LIU Hong-wei, GAO Tie-cheng, LUO Hu-ying, ZHAN Ying, YU Xin. The Study of High-brightness and High-power InGaAlP Red LED[J]. Chinese Journal of Luminescence, 2008,29(2): 330-336DOI:
The Study of High-brightness and High-power InGaAlP Red LED
It is reported that the design and fabrication of high-brightness and high-power InGaAlP ring-shaped interdigitated red LED. High-brightness and high-power InGaAlP LED is a new kind of visible light LED developed in recent years
which is driven by large current capacity
high luminous efficiency and excellent heat resistance. It has been used in various fields
such as large area displays
traffic lights
back-lighting
aviation lighting and so on. As compared with the conventional LED chip
the ring-shaped interdigitated LED chip is more flexible to integrate with other devices
and it leads the more uniform current spreading. The InGaAlP LED epitaxial layer has six layers. From top to bottom
they are the window layer (p-GaP)
the p clad layer(p-InGaAlP)
the active layer between clad layers(i-InGaAlP)
the n clad layer(n-InGaAlP)
distributed Bragg reflectors (DBR) and the n-Substrate(n-GaAs). The epitaxial wafer is tested by scanning electron microscope (SEM) and X-ray double crystal diffraction. The results show the interface of materials is flat
and the integrality and quality of the epitaxial wafer are optimum.The size of chip is 1 mm2.The fabrication of ring-shaped interdigitated LED chip
essentially
is the same as conventional LED chip
involving photolithography
PECVD SiO
2
wet etching
evaporation
lift off and rapid thermal annealing using four masks. To control the widths of mesa and n area precisely
the selecting etch technique has been adopted
using HCL;H
2
O and H
2
O
2
as an InGaAlP etching solution
and the chip is protected by SiO
2
and single layer photoresist during the etching. The fabrication of Ⅲ-Ⅴ compound semiconductor p-type Ohmic contact is more difficult than the fabrication of n-type Ohmic contact. So how to fabricate p-type ohmic contact is a second important technology. AuZn/Au is used to be the p-contact metal in this study
and the chips are sintering for 20 s at 400℃ in N
2
.The
I
-
V
characteristics
light emission spectrum
luminous flux
luminous intensity of this LED have been measured. A good characteristic is obtained with turn-on voltage of 1.5 V and forward current of 500 mA at its forward voltage of 3 V. The peak wavelength is 635 nm
which corresponds to red light
and the full width of half maximum is 16.4 nm at injection current of 350 mA. The luminous intensity is 830 mcd. The color coordinates is x=0.694 3
y=0.305 6 and the color index is 18.4. So we will conclude that the high-brightness and high-power InGaAlP red LED is the first step for a wide scope of general illumination with LED in the future
and it will become new focus in both scientific research and industrial investment for its wide application.
关键词
LEDInGaAlP湿法腐蚀p型欧姆接触
Keywords
LEDInGaAlPwet etchingp-type ohmic contact
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Related Author
ZHANG Min
LIU Dongjie
WEI Yi
DANG Peipei
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LIN Jun
Ji-jian XU
Dan QU
Related Institution
State Key Laboratory of Rare Earth Resource Utilization,Changchun Institute of Applied Chemistry, Chinese Academy of Sciences
School of Applied Chemistry and Engineering, University of Science and Technology of China
Faculty of Materials Science and Chemistry, China University of Geosciences
Center of Excellence for Environmental Safety and Biological Effects, Beijing Key Laboratory for Green Catalysis and Separation, Department of Chemistry and Biology, Beijing University of Technology
State Key Laboratory of Silicon Materials & School of Materials Science and Engineering, Zhejiang University