Absorption and emission spectra of AlN/GaN superlattice structures by DFT methods

Pawel Strak 1Pawel Kempisty 1Stanisław Krukowski 1,2

1. Polish Academy of Sciences, Institute of High Pressure Physics (UNIPRESS), Sokolowska 29/37, Warszawa 01-142, Poland
2. University of Warsaw, Interdisciplinary Centre for Mathematical and Computational Modelling (ICM), Pawinskiego 5a, Warsaw 02-106, Poland


Ambiguity introduced by the strong local electric field induced by the polarization charge density and the background doping strongly disturbs the optical properties of nitrides. The detailed model of the absorption and emission spectra in the vicinity of the fundamental gap is therefore of fundamental importance in studying such systems. Systematic studies were conducted to determine an influence of change of the well/barrier width ratio on the physical properties of AlN/GaN superlattice system, such as the electric field, polarization charges and polarization dipoles. To overcome the Kohn-Sham band gap (BG) underestimation of experimentally measured values, we have applied two different approaches i.e. empirical LDA+U correction method [1] and a method proposed recently by Ferreira et al., called LDA-1/2 which approximately includes the self-energy of excitations in semi-conductors, providing BG energies, effective masses, and band structures in very good agreement with experimental bulk properties [2]. The results obtained within this two approaches were compared. It was shown that the electric fields depend critically on the well-barrier thickness ratio. The overlap of wavefunctions of electrons and holes is calculated, showing considerable separation in space which significantly reduces the oscillator strength of the optical transitions, and consequently, the optical efficiency of nitride based light emitting diodes (LED) and laser diodes (LD). We have determined the dependence of the absorption spectra edge on the type of structure and also on the carrier concentration. Blue shift of the emission peak has been observed when comparing structures with higher dopants concentration.

[1] A. I. Liechtenstein, V. I. Anisimov and J. Zaane, Phys. Rev. B 52, R5467 (1995). 

[2] L.G. Ferreira, M. Marques, and L.K. Teles 78(12), 125116 (2008).


Related papers
  1. GaN/AlN junctions - density functional study
  2. Density Functional Theory (DFT) study of GaN(0001) surface in ammonia rich conditions - influence of doping type
  3. An influence of parallel electric field on the dispersion relation of graphene – a new route to Dirac logics
  4. Drift-diffusion simulations of gallium nitride based heterostructures
  5. Absorption and emission spectra of InN/GaN superlattice structures by DFT methods
  6. Bulk GaAs growth by Contactless Liquid Phase Electroepitaxy
  7. Adsorption of ammonia on hydrogen covered GaN(0001) surface – Density Functional Theory (DFT) study
  8. Adsorption of gallium on GaN(0001) surface in ammonia rich conditions - Density Functional Theory (DFT) study
  9. Density Functional Theory (DFT) study of hydrogen on GaN (0001) surface
  10. Surface structure and diffusion of Si and C adatoms on bare SiC(0001) and SiC(0001) surfaces- density functional theory studies
  11. First-principles calculations of structural and electronic properties of GaN(0001)/Ga interface
  12. A density functional  theory study of the Zn, O, O2, and H2O adsorption on the polar ZnO(0001) and ZnO(000-1) surfaces
  13. Surface morphology of InGaN layers
  14. Modelling of the growth of nitrides in ammonia rich environment
  15. Transport properties on nitrogen at high pressure and temperature: viscosity – MD study.
  16. Adsorption processes during growth of GaN by HVPE
  17. Rietveld refinement for polycrystalline indium nitride
  18. Mass flow and reaction analysis of the growth of GaN layers by HVPE

Presentation: Poster at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, Topical Session 3, by Pawel Strak
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17

Submitted: 2013-04-24 12:51
Revised:   2013-04-24 13:41