Nitrogen-Induced Modification of the Electronic Structure of Group III-N-V Alloys: Preprint Page: 3 of 12
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NITROGEN-INDUCED MODIFICATION OF THE ELECTRONIC STRUCTURE
OF GROUP III-N-V ALLOYS
W. Walukiewicz, W. Shan, J. W. Ager III, D. R. Chamberlin and E. E. Haller,
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley,
J. F. Geisz, D. J. Friedman, J. M. Olson and Sarah R. Kurtz
National Renewable Energy Laboratory, Golden, Colorado 80401
Incorporation of nitrogen in conventional III-V compound semiconductors
to form III-N-V alloys leads to a splitting of the conduction band into two
nonparabolic sub-bands. The splitting can be described in terms of an
anticrossing interaction between a narrow band of localized nitrogen states
and the extended conduction-band states of the semiconductor matrix.
The downward shift of the lower sub-band edge is responsible for the N-
induced reduction of the fundamental band-gap energy. The modification
of the conduction-band structure profoundly affects the optical and
electrical properties of the III-N-V alloys.
It was discovered recently that replacement of group V elements with nitrogen leads to a
dramatic change in the energy-band structure of the standard III-V compounds [1-4].
Incorporation of small concentrations of N into InGaAs results in a large (more than 180
meV per atomic % of N) decrease of the band gap . This can be contrasted with the
standard alloys where the change of the band gap is typically less than 10 meV per
atomic % of any of the component elements. This discovery offers a new, independent
way to control energy gaps and the conduction-band offsets in a large variety of III-V
compounds for optoelectronic applications.
Previous theoretical attempts aimed at an understanding of this large red shift attributed it
to large differences in the atomic size and electronegativities between group V elements
like As or P and N atoms [6-11]. These attempts have met with only limited success
because an accurate treatment of random alloys is very difficult within the existing band
structure calculation methods. In this paper, we show that the effects of substitutional N
on the band structure can be described in terms of a simple model of localized N states
interacting with a band of extended states. The interaction splits the conduction band into
two sub-bands and leads to large enhancement of the electron effective mass. The model
explains many of the existing experimental results and predicts new effects that could be
observed in the group III-N-V semiconductor alloys .
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Walukiewicz, W.; Shan, W.; Ager III, J. W.; Chamberlin, D. R.; Haller, E. E. (Lawrence Berkeley National Laboratory); Geisz, J. F. et al. Nitrogen-Induced Modification of the Electronic Structure of Group III-N-V Alloys: Preprint, article, April 1, 1999; Golden, Colorado. (digital.library.unt.edu/ark:/67531/metadc719897/m1/3/: accessed April 20, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.