Correlation of proton irradiation induced threshold voltage shifts to deep level traps in AlGaN/GaN heterostructures

The impact of proton irradiation on the threshold voltage (V-T) of AlGaN/GaN heterostructures is systematically investigated to enhance the understanding of a primary component of the degradation of irradiated high electron mobility transistors. The value of V-T was found to increase monotonically as a function of 1.8 MeV proton fluence in a sub-linear manner reaching 0.63 V at a fluence of 1 x 10(14) cm(-2). Silvaco Atlas simulations of V-T shifts caused by GaN buffer traps using experimentally measured introduction rates, and energy levels closely match the experimental results. Different buffer designs lead to different V-T dependences on proton irradiation, confirming that deep, acceptor-like defects in the GaN buffer are primarily responsible for the observed V-T shifts. The proton irradiation induced V-T shifts are found to depend on the barrier thickness in a linear fashion; thus, scaling the barrier thickness could be an effective way to reduce such degradation. Published by AIP Publishing.