Spatial distribution of structural degradation under high-power stress in AlGaN/GaN high electron mobility transistors

The two-dimensional spatial distribution of structural degradation of AlGaN/GaN high electron mobility transistors was investigated under high-power electrical stressing using atomic force and scanning electron microscopy. It was found that pits form on the surface of the GaN cap layer at the edges of the gate fingers in the middle of the device. The average pit area and density increase gradually from the edge to the center of the fingers and are more common along inner fingers than fingers. It was also found that pit formation and growth are thermally activated. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4707163]