1. Photoreflectance studiesof N- and Ga-face AlGaN/GaN heterostructures confininga polarisation induced 2DEG
- Author
-
Ruediger Goldhahn, A. Link, A. T. Winzer, Oliver Ambacher, James S. Speck, Y. Smorchkova, C. Buchheim, Umesh K. Mishra, and Martin Stutzmann
- Subjects
Spontaneous polarization ,Condensed matter physics ,Chemistry ,Polarity (physics) ,Electric field ,Heterojunction ,Algan gan ,Condensed Matter Physics ,Conduction band ,Acceptor ,Piezoelectricity ,Electronic, Optical and Magnetic Materials - Abstract
Photoreflectance measurements have been carried out in order to determine the electric field strength F within the topmost layers of Ga-face polarity Al x Ga 1-x N/GaN and N-face polarity GaN/Al x Ga 1-x N/GaN heterostructures containing high-mobile polarisation induced 2DEGs. For both types of samples F decreased from 400 kV/cm at room temperature up to 200 kV/cm when cooling down the structure to T = 5K. Our results strongly emphasise the existence of surface donor and surface acceptor states of the Ga- and N-face samples, respectively. The temperature dependence of F is explained by the change of the piezoelectric and spontaneous polarization. From self-consistent conduction band calculations the bare surface potential was obtained.
- Published
- 2003