skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Excitons Bound to Nitrogen Pairs in GaAs as Seen by Photoluminescence of High Spectral and Spatial Resolution

Abstract

High resolution photoluminescence (PL) spectroscopy was performed on high quality bulk GaAs, lightly doped with the nitrogen isoelectronic impurity. The shallowest nitrogen pair bound exciton center labeled as X{sub 1} revealed a total of six transitions. The photoluminescence lines from a small ensemble of nitrogen centers showed polarization dependent intensity. High spectral resolution PL spectroscopy was combined with confocal spectroscopy experiments performed on a GaAs:N/AlGaAs heterostructure. The high spatial resolution achieved by this technique enables us to localize and examine individual nitrogen bound excitons. Similar spectral structure and polarization dependence was observed for individual N-pair centers in GaAs. Both techniques support the C{sub 2v} symmetry of such isoelectronic impurity centers. The comparison between the PL spectra from an ensemble of nitrogen pairs and individual centers demonstrate the ability of the single impurity technique to lift the orientational degeneracy.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
982274
DOE Contract Number:
AC36-08GO28308
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. B, Condensed Matter and Materials Physics; Journal Volume: 76; Journal Issue: 12, 2007; Related Information: Article No. 125209
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ELEVATORS; EXCITONS; NITROGEN; PHOTOLUMINESCENCE; POLARIZATION; RESOLUTION; SPATIAL RESOLUTION; SPECTRA; SPECTROSCOPY; SUPPORTS; SYMMETRY; Materials Science and Semiconductors; Solid State Spectroscopy

Citation Formats

Karaiskaj, D., Mascarenhas, A., Klem, J. F., Volz, K., Stolz, W., Adamcyk, M., and Tiedje, T.. Excitons Bound to Nitrogen Pairs in GaAs as Seen by Photoluminescence of High Spectral and Spatial Resolution. United States: N. p., 2007. Web. doi:10.1103/PhysRevB.76.125209.
Karaiskaj, D., Mascarenhas, A., Klem, J. F., Volz, K., Stolz, W., Adamcyk, M., & Tiedje, T.. Excitons Bound to Nitrogen Pairs in GaAs as Seen by Photoluminescence of High Spectral and Spatial Resolution. United States. doi:10.1103/PhysRevB.76.125209.
Karaiskaj, D., Mascarenhas, A., Klem, J. F., Volz, K., Stolz, W., Adamcyk, M., and Tiedje, T.. Mon . "Excitons Bound to Nitrogen Pairs in GaAs as Seen by Photoluminescence of High Spectral and Spatial Resolution". United States. doi:10.1103/PhysRevB.76.125209.
@article{osti_982274,
title = {Excitons Bound to Nitrogen Pairs in GaAs as Seen by Photoluminescence of High Spectral and Spatial Resolution},
author = {Karaiskaj, D. and Mascarenhas, A. and Klem, J. F. and Volz, K. and Stolz, W. and Adamcyk, M. and Tiedje, T.},
abstractNote = {High resolution photoluminescence (PL) spectroscopy was performed on high quality bulk GaAs, lightly doped with the nitrogen isoelectronic impurity. The shallowest nitrogen pair bound exciton center labeled as X{sub 1} revealed a total of six transitions. The photoluminescence lines from a small ensemble of nitrogen centers showed polarization dependent intensity. High spectral resolution PL spectroscopy was combined with confocal spectroscopy experiments performed on a GaAs:N/AlGaAs heterostructure. The high spatial resolution achieved by this technique enables us to localize and examine individual nitrogen bound excitons. Similar spectral structure and polarization dependence was observed for individual N-pair centers in GaAs. Both techniques support the C{sub 2v} symmetry of such isoelectronic impurity centers. The comparison between the PL spectra from an ensemble of nitrogen pairs and individual centers demonstrate the ability of the single impurity technique to lift the orientational degeneracy.},
doi = {10.1103/PhysRevB.76.125209},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
number = 12, 2007,
volume = 76,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • High resolution photoluminescence spectroscopy on heavily doped GaAs:N reveals the existence of excitons bound to a nitrogen cluster. The observed transitions are exceedingly sharp, similar to those observed for excitons bound to nitrogen pairs in high quality GaAs with the narrowest transition being only 94 {micro}eV. Moreover, several other features can be observed originating most likely from phonon replicas of the nitrogen pair bound excitons and higher order clusters. However, the main transitions which dominate the photoluminescence spectra are thought to originate from excitons bound to a three nitrogen cluster. The sharp photoluminescence features are superimposed on a broad luminescencemore » band indicating a strong perturbation induced by nitrogen atoms to the host GaAs lattice. The number of the allowed transitions and their polarization dependence provide important information about the arrangement of the nitrogen atoms in the cluster.« less
  • Graphical abstract: Authors demonstrate enhancement in photoluminescence efficiency (7 times) in single layer InAs/GaAs quantum dots using proton irradiation without any post-annealing treatment via either varying proton energy (a) or fluence (b). The increase in PL efficiency is explained by a proposed model before (c) and after irradiation (d). Highlights: {yields} Proton irradiation improved PL efficiency in InAs/GaAs quantum dots (QDs). {yields} Proton irradiation favoured defect and strain annihilation in InAs/GaAs QDs. {yields} Reduction in defects/non-radiative recombination improved PL efficiency. {yields} Protons could be used to improve PL efficiency without spectral shift. {yields} QD based devices will be benefited bymore » this technique to improve device performance. -- Abstract: We demonstrate 7-fold increase of photoluminescence efficiency in GaAs/(InAs/GaAs) quantum dot hetero-structure, employing high energy proton irradiation, without any post-annealing treatment. Protons of energy 3-5 MeV with fluence in the range (1.2-7.04) x 10{sup 12} ions/cm{sup 2} were used for irradiation. X-ray diffraction analysis revealed crystalline quality of the GaAs cap layer improves on proton irradiation. Photoluminescence study conducted at low temperature and low laser excitation density proved the presence of non-radiative recombination centers in the system which gets eliminated on proton irradiation. Shift in photoluminescence emission towards higher wavelength upon irradiation substantiated the reduction in strain field existed between GaAs cap layer and InAs/GaAs quantum dots. The enhancement in PL efficiency is thus attributed to the annihilation of defects/non-radiative recombination centers present in GaAs cap layer as well as in InAs/GaAs quantum dots induced by proton irradiation.« less
  • Measurements of composition of multilayer semiconductor laser wafers were performed with the aid of photoluminescence spectra. Reliable depth profiling of composition is difficult in as-grown wafers, even at low temperature, because the excess-carrier diffusion length is comparable to the layer thicknesses. With adequate reduction of the diffusion length, which in our case was done with ion implantation, the origin of photoluminescence could be restricted to a narrow region close to the excited surface. Samples were prepared for profiling by an angle-etching technique, leaving a controlled angle as small as 0.01/sup 0/ across the wafer, which greatly simplifies profiling measurements. Resultsmore » from composition profiling of a conventional five-layer GaAs-Al/sub x/Ga/sub 1-x/As DH-laser wafer with a depth resolution better than 0.1 ..mu..m are presented.« less
  • Photoluminescence (PL) spectra of excitons bound to the isoelectronic defects [ital B][sub 71][sup 1] (1.137 68 eV principal no-phonon line) created in phosphorus-doped silicon grown in a hydrogen atmosphere as a result of irradiation by thermal neutrons were investigated in magnetic fields up to 12 T and under uniaxial stress. The [ital C][sub 3[ital V]] symmetry of these defects was determined unambiguously from the dependences of the Zeeman splitting and the intensities of spectral components on magnetic-field orientation. The ground state of the bound exciton is split into a doublet with approximately 30 [mu]eV energy separation. This splitting, which ismore » not evident in the zero-field spectra because of the selection rules, results in the appearance of an additional spectral component in a magnetic field. Using group theoretical methods we constructed a Hamiltonian for excitons bound to the [ital B][sub 71][sup 1] isoelectronic center, which takes into account electron-hole coupling and interaction with external perturbations. The phenomenological parameters of this Hamiltonian were determined from the optimal fit between theoretical and experimental dependences of the PL peak positions and their amplitudes on magnetic field and uniaxial stress. The proposed model of these bound excitons explains all of our experimental observations.« less