Transcript 下載/瀏覽

GaN-Based MSM Photodetectors
Prepared on Patterned Sapphire
Substrates
Shoou-Jinn Chang, Member, IEEE, Y. D. Jhou, Y. C. Lin, S. L. Wu, C. H. Chen,
T. C. Wen, and L. W. Wu
IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 20, NO. 22,
NOVEMBER 15, 2008
陳詠升
Outline

Introduction
 Experiments
 Results and discussion
 Conclusion
 References
Introduction
GaN materials exhibit high thermal
conductivity and wide direct bandgap.
 These properties make GaN-based
materials excellent light emitters.

Experiments
受光面積：150 × 150μm2
指叉狀電極： 寬10μm 長150μm 10μm
Ni/Au
GaN 1μm
GaN 1μm
sapphire
sapphire
間距3μm
Results and discussion
Fig. 1. AFM images of (a) sample A prepared on conventional flat sapphire
substrate and (b) sample B prepared on PSS.
FWHM
sample A=561 arcsec
sample B=358 arcsec
Fig. 2. Asymmetrical (102) DCXRD rocking curves for the two samples.
( sample A prepared on conventional flat sapphire substrate and sample B prepared on PSS.)
Fig. 3. I-Vcharacteristics of the two fabricated MSM PDs measured in
dark.Inset shows photograph of the fabricated devices.
( sample A prepared on conventional flat sapphire substrate and sample B prepared on PSS.)
Responsivity 1V
sample A =0.03 A/W sampleB=0.31 A/W
Fig. 4. Spectral responses of (a) sample A prepared on conventional flat
sapphire substrate and (b) sample B prepared on PSS.
Fig. 5. Measured responsivity at 360 nm as a function of applied
bias for the two PDs.
( sample A prepared on conventional flat sapphire substrate and sample B prepared on PSS.)
Conclusion

GaN-based UV MSM PDs prepared on PSS and on a
conventional flat sapphire substrate were both fabricated. It
was found that we could suppress the generation of TD,
improve crystal quality, and thus reduce internal gain of
the PDs by using PSS.
References


W. H. Lan, “Wavelength shift of gallium nitride light emitting diode
with p-down structure,” IEEE Trans. Electron. Dev., vol. 52, pp.1217–
1219, 2005.
S. W. Lee, D. C. Oh, H. Goto, J. S. Ha, H. J. Lee, T. Hanada, M.
W.Cho, T. Yao, S. K. Hong, H. Y. Lee, S. R. Cho, J. W. Choi, J. H.
Choi,J. H. Jang, J. E. Shin, and J. S. Lee, “Origin of forward leakage
current in GaN-based light-emitting devices,” Appl. Phys. Lett., vol. 89,
2006,Article 132117.