Focused-laser-enabled p-n junctions in graphene field-effect transistors

Young Duck Kim, Myung Ho Bae, Jung Tak Seo, Yong Seung Kim, Hakseong Kim, Jae Hong Lee, Joung Real Ahn, Sang Wook Lee, Seung Hyun Chun, Yun Daniel Park

Research output: Contribution to journalArticlepeer-review

74 Scopus citations


With its electrical carrier type as well as carrier densities highly sensitive to light, graphene is potentially an ideal candidate for many optoelectronic applications. Beyond the direct light-graphene interactions, indirect effects arising from induced charge traps underneath the photoactive graphene arising from light-substrate interactions must be better understood and harnessed. Here, we study the local doping effect in graphene using focused-laser irradiation, which governs the trapping and ejecting behavior of the charge trap sites in the gate oxide. The local doping effect in graphene is manifested by large Dirac voltage shifts and/or double Dirac peaks from the electrical measurements and a strong photocurrent response due to the formation of a p-n-p junction in gate-dependent scanning photocurrent microscopy. The technique of focused-laser irradiation on a graphene device suggests a new method to control the charge-carrier type and carrier concentration in graphene in a nonintrusive manner as well as elucidate strong light-substrate interactions in the ultimate performance of graphene devices.

Original languageEnglish
Pages (from-to)5850-5857
Number of pages8
JournalACS Nano
Issue number7
StatePublished - 23 Jul 2013


  • charge trap
  • focused laser
  • graphene
  • local doping effect
  • p-n junction
  • photocurrent


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