GaN MSM photodetectors with an unactivated Mg-doped GaN cap layer and sputtered ITO electrodes

K. H. Lee, P. C. Chang, S. J. Chang, C. L. Yu, Y. C. Wang, S. L. Wu

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

GaN UV metal-semiconductor-metal photodetectors (MSM PDs) with an unactivated Mg-doped cap layer and sputtered indium tin oxide (ITO) were fabricated. Compared with conventional MSM PDs without a cap layer, it was found that we could achieve a significantly much smaller dark current, larger UV to visible rejection ratio, and larger normalized detectivity by inserting an unactivated Mg-doped GaN cap layer. The dark leakage current for the MSM PDs with an unactivated Mg-doped GaN cap layer was shown to be about ten orders of magnitude smaller than that for the conventional MSM PDs. Under a 0.5 V bias, the measured responsivity and UV-to-visible rejection ratio were 0.017 A/W and 1.44× 104, respectively, for the MSM PDs with an unactivated Mg-doped GaN cap layer. This result could be attributed to the thicker and higher potential barrier and effective surface passivation after inserting this in situ grown cap layer. With a 1 V applied bias, it was also found that we could achieve a lower noise level and a higher normalized detectivity of 2.67× 1010 cm Hz0.5 W-1 by inserting an unactivated Mg-doped GaN cap layer into MSM PDs.

Original languageEnglish
Pages (from-to)J165-J167
JournalJournal of the Electrochemical Society
Volume155
Issue number6
DOIs
Publication statusPublished - 2008

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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