We present the results of a radiation damage experiment on <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm Al}_{\rm x}{\rm Ga}_{1-{\rm x}}{\rm N/GaN}$</tex></formula> high electron mobility transistors. The basic mechanism underlying the observed high radiation tolerance appears to be a strong internal piezoelectric field near the two-dimensional electron gas that causes scattered carriers to be reinjected.
