Development of magneto-optic sensors in the ultra-violet region employing graphene quantum architectures

Abstract

We report the magneto-optic response of “puckered” graphene quantum sheets (GQSs) decorated with graphene quantum dots (GQDs) of ∼5 nm in size. The magneto-optic coupling helps in improving the response of the photodetectors. The enhancement ratio (R_OFF/R_ON) of the commercial bare and coated light-dependent resistors (LDRs) is analyzed in the absence and presence of a magnetic field and UV light. The magnetic coupling is exhibited due to the availability of unpaired electrons in GQSs. The Raman study supports the presence of defect sites leading to spin polarization of the delocalized electrons under the influence of a transverse magnetic field. The magnetic field increases the conductivity by allowing charge carriers to travel in a curved trajectory while experiencing the Lorentz force. The measured response and decay times are 5.56 and 93.28 ms, respectively, which are comparable to those of the commercial LDRs. The cumulative contribution of higher sp²% (87%), enhanced I_2D/I_D (∼25) and lower I_D/I_G (0.02) ratios enhances the magneto-optic response by ∼15% at 300 K with the variation of magnetic field from 0 to 0.7 T. The synthesized unique puckered graphene quantum materials showing reasonably improved magneto-optic characteristics may find their application in various quantum technologies.