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 (10 (11) over bar) oriented In(0.15)Ga(0.85)N 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/m(2). 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.