Gamma-ray radiation effects in graphene-based transistors with h-BN nanometer film substrates

Abstract

Radiation effects on graphene field effect transistors (GFETs) with hexagonal boron nitride (h-BN) thin film substrates are investigated using 60Co gamma-ray radiation. This study examines the radiation response using many samples with varying h-BN film thicknesses (1.6 and 20 nm thickness) and graphene channel lengths (5 and 10 μm). These samples were exposed to a total ionizing dose of approximately 1 Mrad(Si). I-V measurements were taken at fixed time intervals between irradiations and postirradiation. Dirac point voltage and current are extracted from the I-V measurements, as well as mobility, Dirac voltage hysteresis, and the total number of GFETs that remain properly operational. The results show a decrease in Dirac voltage during irradiation, with a rise of this voltage and permanent drop in Dirac current postirradiation. 1.6 nm h-BN substrate GFETs show an increase in mobility during irradiation, which drops back to preirradiation conditions in postirradiation measurements. Hysteretic changes to the Dirac voltage are the strongest during irradiation for the 20 nm thick h-BN substrate GFETs and after irradiation for the 1.6 nm thick h-BN GFETs. Failure rates were similar for most GFET types during irradiation; however, after irradiation, GFETs with 20 nm h-BN substrates experienced substantially more failures compared to 1.6 nm h-BN substrate GFETs.