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The Thickness Effect of pAlGaN Blocking Layer in
UV-A Bandpass Photodetectors
C. K. Wang, T. K. Ko, C. S. Chang, S. J. Chang, Y. K. Su, T. C. Wen, C. H.
Kuo, and Y. Z. Chiou
IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 17, NO. 10, OCTOBER 2005
D.J. Sun
Outline
• Introduction
• Experiment
• Results and discussion
• Conclusion
• References
Introduction
• A nitride-based photodetector is a good
candidate for visible-blind UV detectors.
• By modulating the Al mole fraction can tune
the optical bandwidth and central wavelength
of the photodetectors’s UV responsivity.
Experiment
p-elecrode (+電極)
TCL Ni-Au(50/50Å)
four-pair InGaN–GaN
10nm p-type GaN
60,(150,300)nm blocking layer
active/absorption 0.5 µm
undoped GaN
4µm n-GaN at 1050 ℃
respectively deposited
p-type Al0.1Ga0.9N
n-elecrode (-電極)
Ti-Al-Ti-Au
(100/1000/200/5000Å)
30-nm buffer at 550 ℃
Sapphire
hight temperature treatment
Experiment
Fig. 2. Spectral responsivities of nitride-based p-i-n bandpass photodetectors
at room temperature.
Results and discussion
Results and discussion
Fig. 3. Current–voltage characteristics of the nitride-based p-i-n bandpass
-1
photodetectors at room temperature with fitting curve. R = (dV=dI) at zero bias.
感測率
Results and discussion
Conclusion
• The peak responsivities were estimated to be 0.13 A/W at
356nm for 300-nm-thick p-Al0.1Ga0.9N blocking layer,
respectively, corresponding to a quantum efficiency of
around 46%.
• The photodetectors exhibit a 20-V break-down voltage and
a small dark current of around 3 pA at 5-V reverse bias.
References
• C. K. Wang, T. K. Ko, C. S. Chang, S. J. Chang,
Y. K. Su, T. C. Wen, C. H. Kuo, and Y. Z. Chiou
“The Thickness Effect of p-AlGaN Blocking
Layer in UV-A Bandpass Photodetectors” IEEE
PHOTONICS TECHNOLOGY LETTERS, VOL.
17, NO. 10, OCTOBER 2005
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