Graphene for radio frequency electronics and infrared thermal imaging

Abstract

The aim of this thesis is two-fold: The first is to develop a reliable processing technology for CVD graphene devices for applications in graphene circuits, i.e. mixers, frequency multipliers and phase key shifters. The performance of current graphene circuits has been limited to below 1.5 GHz due to issues with contact resistances and materials quality. Through improved processing techniques and studies about interface preparation between graphene and metal contacts - we demonstrate improved graphene-metal interactions to allow for CVD-graphene based circuits operating at >10 GHz. The second part of this thesis involves exploring graphene as a new infrared photoactive and thermally sensitive material for sensors in the IR spectrum (80 meV < Eph < 250 meV), which have applications ranging from thermography and night vision systems to nanoscale chemical spectroscopy. In this thesis, we will focus on graphene's intrinsic detection mechanisms at much lower photon energies (~ 125 meV) and resolve experimentally the dominant infrared detection mechanism in graphene. We find in the infrared that graphene's electronically tunable Seebeck Coefficient (~50-100 [mu]V/K) dominates at very low photon energies making graphene suitable as a nanoscale thermal detector. Utilizing this design concept, we discuss graphene's suitability for infrared imaging, as well as, other thermal applications such as low cost transparent temperature sensors.