Radiation Effects in Diamond Substrates and Transistors

Field effect transistors (FET) based on diamond substrate and with epitaxial lattice matched layer and with a 2 – dimensional hole gas (2DHG) as the conduction channel are reported in the present work A key aspect of diamond-based FETs is their promise of radiation hardness. Radiation hardness results are reported. Cyclotron generated proton irradiation effects on the present diamond FETs are reported., A panoramic gamma irradiator with 60Co as the source material was used for gamma irradiation on diamond-based FETs as well. Diamond FETs were irradiated with protons at 150 keV and fluence of 1,012 particles/cm. Diamond-based devices are expected to exhibit radiation robustness, due to the high binding energy of carbon atoms. However, the present of diamond FETs with two-dimensional conducting channels, (1) H-terminated, and (2) delta-doped, may be susceptible to radiation degradation. The gamma radiation tolerance of H-terminated diamond-based field effect transistors (FETs) at low dose irradiation i.e. 100 kRad and high dose irradiation up to 26.3 Mrad is reported. A modest decrease in output characteristics was observed for low dose irradiation. In contrast, a significant increase in drain current output, similar to an annealing effect, was observed for high dose irradiation. In addition, the FETs with H-terminated and delta-doped channels tolerance to 152 keV proton irradiation with 1.03 10 fluence were characterized via Hall measurements. The diamond FETs exhibited increased resistivities, and decreased mobilities and carrier concentrations post-irradiation. The activation energies for conductivity changes indicating trap state formation and generation as the radiation induced mechanism.