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Contactless electroreflectance studies of the Fermi level position at the air/GaN interface: Bistable nature of the Ga-polar surface
- Source :
- Applied Surface Science. 396:1657-1666
- Publication Year :
- 2017
- Publisher :
- Elsevier BV, 2017.
-
Abstract
- In this paper we show that the surface Fermi level of Ga-polar GaN exhibits a bistable behavior allowing it to be located at two distinct energetic positions at the air/GaN interface which is unusual for other III–V semiconductors such as GaAs or GaSb. To determine the Fermi level position at the air/GaN interface we perform contactless electroreflectance measurements on specially designed UD+ structures [GaN(undoped)/GaN(highly doped)/substrate] doped by Si and Mg. Analyzing the period of Franz-Keldysh oscillation we determine the built-in electric field in the undoped (U) layer. These studies coupled with numerical solutions of the Poisson equation allowed us to determine the position of the Fermi level at the air/GaN interface. We observe a change in the band bending correlated to different Fermi level positions in the doped (D+) layer. We show that depending on the doping type in the D+ layer the Fermi level at the air/GaN interface is located in the upper or lower singularity of surface density of states (SDOS) for Si or Mg doping of D+ layer, respectively. We support our findings with the density functional theory calculations of the SDOS and the dependence of the Fermi level position on the doping concentration in the bulk of a GaN slab.
- Subjects :
- Materials science
General Physics and Astronomy
Gallium nitride
02 engineering and technology
01 natural sciences
Condensed Matter::Materials Science
symbols.namesake
chemistry.chemical_compound
Condensed Matter::Superconductivity
Electric field
0103 physical sciences
010302 applied physics
Condensed matter physics
business.industry
Fermi level
Doping
Surfaces and Interfaces
General Chemistry
021001 nanoscience & nanotechnology
Condensed Matter Physics
Surfaces, Coatings and Films
Band bending
Semiconductor
chemistry
symbols
Density of states
Optoelectronics
Condensed Matter::Strongly Correlated Electrons
Density functional theory
0210 nano-technology
business
Subjects
Details
- ISSN :
- 01694332
- Volume :
- 396
- Database :
- OpenAIRE
- Journal :
- Applied Surface Science
- Accession number :
- edsair.doi...........aea7d70b7918716f3999115ade363cbc