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Design and optimization of high -speed large -area intermediate-temperature grown GaAs metal -semiconductor -metal photodetectors

Purdue University
Publication Date
  • Engineering
  • Electronics And Electrical|Physics
  • Optics
  • Communication


With the advent of plastic fiber-optic communication links in recent years, large-area photodetectors have become very important. Historically, large-area photodetectors have suffered from large capacitances leading to long fall-time transients. MSM photodetectors have very low device capacitances and are well suited for planar integration. However, normal temperature grown GaAs (NTG-GaAs) MSM-PDs have hole-tailing effects in the fall-time transient making them unsuitable for use in communication links. In this thesis, we propose that intermediate temperature grown GaAs (ITG-GaAs) be used as the light absorption layer in a MSM-PD. This gives us the ability to tailor the carier-lifetime to be slightly longer than the transit time, thereby suppressing the hole-tailing effect. The ultra-low device capacitance of the MSM-PD makes practical large-area detectors possible. Finally, with the use of both ITG layers and NTG layers, we can suppress the hole-tailing effect and maintain a high responsivity. This would result in an optimized device structure for large-area applications. ^

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