The physical mechanism of dispersion caused by AlGaN/GaN buffers on Si and optimization for low dispersion

In this paper a measurement methodology, using a two-dimensional electron gas (2DEG) resistor, is used to evaluate the dispersion of three different type of buffers, namely a step graded buffer, a buffer with low temperature (LT) AlN interlayers and a superlattice buffer. Together with a dedicated Design of Experiments (DOE), these measurements allowed us to identify the physical origin of the dispersion and identify the key parts of the buffer which influence the buffer-induced dispersion of the 2DEG.