Simultaneous observation of two dimensional electron gas and polarization in AlGaN/GaN heterostructure using scanning nonlinear dielectric microscopy

The AlGaN/GaN heterostructure has two-dimensional electron gas (2DEG) and electric polarization. We observed both of them simultaneously in the cross section of the AlGaN/GaN heterostructure by scanning nonlinear dielectric microscopy (SNDM), which can visualize both carrier and polarization distributions. The AlGaN/GaN heterostructure was cross-sectioned at an angle of 20° from the [0001] axis and, hence, the perpendicular components of the polarizations of AlGaN and GaN were observed. Moreover, the 2DEG distribution was confirmed in a range of >10nm at the AlGaN/GaN interface.