liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Optical characterization of dilute nitride semiconductors and related quantum structures
Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Dilute nitrides (i.e. nitrogen-containing, anion-mixed III-V ternary and quaternary alloys) have recently attracted much attention due to their unusual fundamental properties promising for device applications in optoelectronics and photonics, such as highly efficient and low cost near infrared lasers, efficient visible light emitting diodes (LEDs), multi-junction solar cells, as well as heterojunction bipolar transistors (HBTs). In order to fully explore the potential of these new materials, detailed knowledge on their fundamental and material-related properties is required.

The work presented in this thesis focuses on optical studies of the electronic structure, radiative recombination processes and also characterization of material properties of several dilute nitrides systems that are relevant to device applications, such as GaNP/GaP, GaNP/Si, GaNAs/GaAs and GaInNP/GaAs. The thesis is divided into two parts. The first part includes five chapters that give a general introduction to the research field and also describes experimental methods utilized in the research work. The second part contains seven original scientific papers.

Papers I and II report detailed studies of effects of post-growth hydrogen incorporation on the electronic structure of GaNAs and GaNP alloys by using photoluminescence (PL), PL excitation (PLE), and Raman spectroscopies, as well as high resolution X-ray diffraction (HRXRD) measurements. Introduction of hydrogen in the alloys was found to cause passivation of N-related localized states. Additionally, profound and rather astonishing changes in the band structure upon H incorporation were observed, such as a recovery of the bandgap energies of the parental GaAs and GaP, i.e. deactivation of the N-induced bandgap bowing. In GaNP, this was accompanied by a reduction in the N-induced coupling between the conduction band states. Raman spectroscopy has showed that these effects are related to hydrogeninduced breaking of the Ga-N bond. Raman and HRXRD measurements have also shown that the hydrogenation caused a strong expansion of the GaNP lattice, which changes the sign of strain from tensile strain in the as-grown GaNP epilayers to compressive strain after hydrogenation, due to formation of complexes between N and H.

Paper III-IV discuss optical quality and defect properties of GaNP/Si and GaNP /GaP alloys, as well as effects of rapid thermal annealing (RTA). By employing a variety of optical characterization techniques including cathodoluminescence (CL), cw- and time-resolved PL, PLE, and optically detected magnetic resonance (ODMR), high optical quality of the GaN0.018P0.982 epilayers lattice matched to Si substrates was demonstrated and was shown to be comparable to that of the “state-of-the-art" GaNP alloys grown on GaP substrates. The growth of GaNP on Si is, however, found to facilitate the formation of several point defects, including complexes involving Ga interstitials (Gai). A reduction and removal of competing non-radiative point defects by RTA has been concluded to be responsible for a substantial increase in radiative efficiency of the GaNP epilayers subjected to the post-growth annealing, evident from reduced thermal quenching of the PL intensity as well as from a substantial increase in carrier lifetime at room temperature.

Papers V-VII are devoted to detailed studies of Ga0.46In0.54NxP1-x alloys lattice matched to GaAs, by using cw- and time-resolved PL, PLE, and optically detected cyclotron resonance (ODCR) measurements. The type-II band alignment at the Ga0.46In0.54NxP1-x/GaAs interface was concluded with x ≥ 0.5% based on (i) highly efficient photoluminescence upconversion (PLU) observed in the N containing alloys and (ii) appearance of a near-infrared PL emission attributed to the spatially indirect type-II transitions. Compositional dependence of the conduction band offset at the GayIn1-yNxP1-x/GaAs interface was also estimated. Origin of the PLU process was determined as being due to two-step two-photon absorption (TS-TPA). Different from other direct band gap dilute nitrides, the low temperature PL emission was shown to largely arise from radiative transitions involving spatially separated localized electronhole pairs. The observed charge separation was tentatively attributed to the long range CuPt ordering promoted by the presence of nitrogen.

Place, publisher, year, edition, pages
Institutionen för fysik, kemi och biologi , 2006. , 53 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 995
Keyword [en]
Dilute nitrides, optoelectronics, photonics
National Category
Atom and Molecular Physics and Optics
Identifiers
URN: urn:nbn:se:liu:diva-7290ISBN: 91-85457-97-3 (print)OAI: oai:DiVA.org:liu-7290DiVA: diva2:22312
Public defence
2006-02-10, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Available from: 2006-09-07 Created: 2006-09-07 Last updated: 2012-11-14
List of papers
1. Hydrogen-induced improvements in optical quality of GaNAs alloys
Open this publication in new window or tab >>Hydrogen-induced improvements in optical quality of GaNAs alloys
Show others...
2003 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 82, no 21, 3662-3665 p.Article in journal (Refereed) Published
Abstract [en]

Strong suppression of potential fluctuations in the band edges of GaNAs alloys due to postgrowth hydrogen treatment, which is accompanied by a reopening of the alloy band gap, is revealed from temperature-dependent photoluminescence (PL) and PL excitation measurements. The effect likely indicates preferential trapping of hydrogen near the lattice sites with the highest nitrogen content. A remarkable improvement in the radiative efficiency of the alloys at room temperature is also demonstrated and is ascribed to efficient hydrogen passivation of competing nonradiative centers.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-45047 (URN)10.1063/1.1578513 (DOI)79491 (Local ID)79491 (Archive number)79491 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13
2. Direct experimental evidence for unusual effects of hydrogen on the electronic and vibrational properties of GaNxP1−x alloys: a proof for a general property of dilute nitrides
Open this publication in new window or tab >>Direct experimental evidence for unusual effects of hydrogen on the electronic and vibrational properties of GaNxP1−x alloys: a proof for a general property of dilute nitrides
Show others...
2004 (English)In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 70, no 24, 245215-245219 p.Article in journal (Refereed) Published
Abstract [en]

Direct experimental evidence for dramatic effects of hydrogen incorporation on the electronic structure and lattice properties of GaNxP1−x alloys is presented. By employing photoluminescence excitation spectroscopy, postgrowth hydrogenation is shown to reopen the band gap of the GaNP alloys and to efficiently reduce the N-induced coupling between the conduction band states. By Raman spectroscopy, these effects are shown to be accompanied by hydrogen-induced breaking of the Ga-P bond in the alloy, evident from disappearance of the corresponding vibrational mode. According to the performed Raman and x-ray diffraction measurements, the hydrogenation is also found to cause a strong expansion of the GaNP lattice, which changes the sign of strain from tensile in the as-grown GaNP epilayers to compressive in the posthydrogenated structures, due to the formation of complexes between N and H.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-45014 (URN)10.1103/PhysRevB.70.245215 (DOI)79416 (Local ID)79416 (Archive number)79416 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13
3. Evaluation of optical quality and defect properties of GaNxP1−x alloys lattice matched to Si
Open this publication in new window or tab >>Evaluation of optical quality and defect properties of GaNxP1−x alloys lattice matched to Si
Show others...
2004 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 85, 6347- p.Article in journal (Refereed) Published
Abstract [en]

By using a variety of optical characterization techniques, including cathodoluminescence, temperature-dependent cw- and time-resolved photoluminescence (PL), and PL excitation spectroscopies, high optical quality of the GaN0.018P0.982 epilayers lattice matched to Si substrates is demonstrated and is shown to be comparable to that of the “state-of-the-art” GaNP alloys grown on GaP substrates. The growth of GaNP on Si is, however, found to facilitate the formation of several point defects, including complexes involving Ga interstitial atoms (Gai).

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-45010 (URN)10.1063/1.1839286 (DOI)79412 (Local ID)79412 (Archive number)79412 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13
4. Effects of rapid thermal annealing on optical properties of GaNxP1−x alloys grown by solid source molecular beam epitaxy
Open this publication in new window or tab >>Effects of rapid thermal annealing on optical properties of GaNxP1−x alloys grown by solid source molecular beam epitaxy
Show others...
2005 (English)In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 20, no 5, 353-356 p.Article in journal (Refereed) Published
Abstract [en]

Temperature-dependent photoluminescence (PL), PL excitation and time-resolved PL measurements were employed to study the effects of rapid thermal annealing (RTA) on optical properties of GaNxP1−x alloys grown by solid source molecular beam epitaxy. A substantial increase in radiative efficiency of GaNP epilayers, which is especially pronounced for the high-energy PL component, was achieved after RTA and is attributed to annealing out of competing non-radiative centres. The latter is evident from reduced quenching of the PL intensity with increasing measurement temperature, which results in a strong increase (up to 18 times) in the PL intensity at room temperature (RT), as well as from a substantial increase in carrier lifetime at RT deduced from time-resolved PL measurements.

National Category
Natural Sciences Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-30725 (URN)10.1088/0268-1242/20/5/005 (DOI)16338 (Local ID)16338 (Archive number)16338 (OAI)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2017-12-13
5. Band alignment in GaInNP/GaAs heterostructures grown by gas-source molecular-beam epitaxy
Open this publication in new window or tab >>Band alignment in GaInNP/GaAs heterostructures grown by gas-source molecular-beam epitaxy
Show others...
2005 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 86, no 26, 261904- p.Article in journal (Refereed) Published
Abstract [en]

Low-temperature photoluminescence (PL), PL excitation, and optically detected cyclotron resonance measurements are employed to determine band alignment in GaInNP/GaAs heterostructures grown by gas-source molecular-beam epitaxy. The type II band alignment at the Ga0.46In0.54NxP1−x/GaAs interface is concluded for the alloys with x ≥ 0.5% based on (i) highly efficient PL upconversion observed in the N containing samples and (ii) appearance of a near-infrared PL emission attributed to the spatially indirect type II transitions. Compositional dependence of the conduction band offset at the Ga1−yInyNxP1−x/GaAs interface is also estimated.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-50479 (URN)10.1063/1.1952586 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-12
6. Photoluminescence upconversion in GaInNP/GaAs heterostructures grown by gas source molecular beam epitaxy
Open this publication in new window or tab >>Photoluminescence upconversion in GaInNP/GaAs heterostructures grown by gas source molecular beam epitaxy
Show others...
2006 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 99, no 7, 073515- p.Article in journal (Refereed) Published
Abstract [en]

Properties of photoluminescence (PL) upconversion (PLU) in GaInNP/GaAs heterostructures are studied in detail by employing a number of optical spectroscopies. Based on excitation power dependent and temperature dependent PL measurements, the upconverted PL from GaInNP under optical excitation below its band gap is attributed to radiative transitions involving spatially separated localized electron-hole pairs, which is of a similar origin as the near-band-gap emission detected under optical excitation above the GaInNP band gap. The PLU process is shown to be largely promoted by increasing N content in the GaInNP alloys, due to a N-induced change in the band alignment at the GaInNP/GaAs heterointerface from the type I in the N-free structure to the type II in the samples with N compositions exceeding 0.5%. A possible mechanism for the energy upconversion is discussed in terms of two-step two-photon absorption. The photon recycling effect is shown to be important for the structures with N = 1%.

National Category
Engineering and Technology Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-50252 (URN)10.1063/1.2188087 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-12
7. Radiative recombination of GaInNP alloys lattice matched to GaAs
Open this publication in new window or tab >>Radiative recombination of GaInNP alloys lattice matched to GaAs
Show others...
2006 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 88, no 1, 011919- p.Article in journal (Refereed) Published
Abstract [en]

Cw- and time-resolved photoluminescence (PL) spectroscopy is employed to evaluate dominant mechanisms for light emission in GayIn1−yNxP1−x alloys grown by gas source molecular-beam epitaxy on GaAs substrates. Different from other direct band gap dilute nitrides, the low temperature PL emission was shown to be largely attributed to radiative transitions involving spatially separated localized electron-hole pairs. The observed charge separation is tentatively attributed to the long range CuPt ordering promoted by the presence of nitrogen.

National Category
Natural Sciences Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-36494 (URN)10.1063/1.2161118 (DOI)31451 (Local ID)31451 (Archive number)31451 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13

Open Access in DiVA

No full text

Authority records BETA

Izadifard, Morteza

Search in DiVA

By author/editor
Izadifard, Morteza
By organisation
Department of Physics, Chemistry and BiologyThe Institute of Technology
Atom and Molecular Physics and Optics

Search outside of DiVA

GoogleGoogle Scholar

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 434 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf