Unambiguous evidence of the existence of polarization field crossover in a semipolar InGaN/GaN single quantum well

We present an electroreflectance study of the piezoelectric field in a semipolar (1011¯) oriented In0.15Ga0.85N quantum well (QW). The flatband condition is precisely determined by examining the zero-crossing of the electroreflectance signal. The polarization field determined by the flatband condition is 840±150 kV/cm, in the direction opposite to the built-in field. The corresponding polarization charge at the heterointerface is 0.008±0.002 C/m2. Our experimental result indicates that in the semipolar InGaN/GaN QW there is a crossover angle between the C-axis and the growth direction where the polarization field vanishes.