Radiation Effects in Diamond pHEMTs

Abstract

Field effect transistors (FET) based on diamond have 2-dimensional hole gas (2DHG) as conduction channel. In terms of usability in harsh environment, an important aspect of diamond-based FETs is its promise of radiation hardness. Because of high binding energy of diamond, diamond transistors are predicted to be radiation hard. However, the way radiation affects the 2DHG conduction layer is unknown. This may be a problem as radiation may disrupt the 2D hole concentrations in the 2DHG channel. In this work, radiation effects in diamond with 2DHG layer is explored in two ways: (1) Using Hall effect measurements to monitor changes in transport properties, and (2) measuring current-voltage characteristics for the three-terminal devices to analyze changes in their device properties. Two different types of radiation were used. A cyclotron was used for proton irradiation on diamond substrates, and a high capacity dry cell, panoramic gamma irradiator with 60Co as source material was used for gamma irradiation on diamond-based FETs. Diamond substrates were irradiated with protons at 152 keV and fluence of 1012 particles/cm2. Likewise, diamond-based FETs were irradiated with gammas from a total dose of 100kRad up to 10 MRads and exhibited an annealing effect. ACKNOWLEDGEMENTS The authors thank the University of Maryland NanoCenter, the University of Maryland Radiation Facilities and Argonne National Laboratory for equipment and staff support. The effort depicted is sponsored by the Department of Defense, Defense Threat Reduction Agency under Grant No. HDTRA1-17-1-0007. The content of this information does not necessarily reflect the position or the policy of the federal government, and no official endorsement should be inferred. The authors acknowledge the assistance in material preparation from Jim Butler of EuclidTech Labs.