Partially polycrystalline GaN1-xAsx alloys grown on GaAs in the middle composition range achieving a smaller band gap

Hong Ming Wu, Kuang-I Lin, Yu Xuan Liu, Hao Hsiung Lin, Yung Chen Cheng

Research output: Contribution to journalArticle

Abstract

GaN1-xAsx alloys have been successfully grown on (100) GaAs substrates over a wide composition range (0.15 x 0.98) by plasma-assisted molecular beam epitaxy. In the middle composition range, the weak and broad (111) diffraction peaks are observed in the X-ray diffraction patterns. These diffraction peaks most likely come from small crystalline grains within the amorphous matrix and are unlike the entirely amorphous GaNAs alloys grown on sapphire and Pyrex glass. A transmission electron microscopy micrograph of the GaN0.50As0.50 alloy also shows a weak periodic structure consisting of small polycrystalline grains. To study the band gap and the As-affected spin-orbit band to conduction-band minimum transition, photomodulated reflectance is utilized. The band gap energies range from 0.78 to 2.15 eV (3.4 eV for end-point compounds GaN). Finally, the original and modified band anticrossing (BAC) models for GaNAs alloys were thoroughly verified over the entire composition range. Remarkably, the band gap energies of the partially polycrystalline GaNAs alloys agree well with those obtained using the original BAC model in the middle composition range because the model has been developed for crystalline materials. These results improve the growth of highly mismatched GaNAs alloys with different substrates and should expedite studies of high-efficiency multijunction solar cells fabricated using such a single ternary alloy system.

Original languageEnglish
Article number081202
JournalJapanese Journal of Applied Physics
Volume56
Issue number8
DOIs
Publication statusPublished - 2017 Aug 1

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Energy gap
Chemical analysis
Diffraction
Crystalline materials
Ternary alloys
Periodic structures
Amorphous alloys
Substrates
Electron transitions
Conduction bands
Molecular beam epitaxy
Sapphire
ternary alloys
Diffraction patterns
borosilicate glass
diffraction
Orbits
conduction bands
Transmission electron microscopy
sapphire

All Science Journal Classification (ASJC) codes

  • Engineering(all)
  • Physics and Astronomy(all)

Cite this

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title = "Partially polycrystalline GaN1-xAsx alloys grown on GaAs in the middle composition range achieving a smaller band gap",
abstract = "GaN1-xAsx alloys have been successfully grown on (100) GaAs substrates over a wide composition range (0.15 x 0.98) by plasma-assisted molecular beam epitaxy. In the middle composition range, the weak and broad (111) diffraction peaks are observed in the X-ray diffraction patterns. These diffraction peaks most likely come from small crystalline grains within the amorphous matrix and are unlike the entirely amorphous GaNAs alloys grown on sapphire and Pyrex glass. A transmission electron microscopy micrograph of the GaN0.50As0.50 alloy also shows a weak periodic structure consisting of small polycrystalline grains. To study the band gap and the As-affected spin-orbit band to conduction-band minimum transition, photomodulated reflectance is utilized. The band gap energies range from 0.78 to 2.15 eV (3.4 eV for end-point compounds GaN). Finally, the original and modified band anticrossing (BAC) models for GaNAs alloys were thoroughly verified over the entire composition range. Remarkably, the band gap energies of the partially polycrystalline GaNAs alloys agree well with those obtained using the original BAC model in the middle composition range because the model has been developed for crystalline materials. These results improve the growth of highly mismatched GaNAs alloys with different substrates and should expedite studies of high-efficiency multijunction solar cells fabricated using such a single ternary alloy system.",
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Partially polycrystalline GaN1-xAsx alloys grown on GaAs in the middle composition range achieving a smaller band gap. / Wu, Hong Ming; Lin, Kuang-I; Liu, Yu Xuan; Lin, Hao Hsiung; Cheng, Yung Chen.

In: Japanese Journal of Applied Physics, Vol. 56, No. 8, 081202, 01.08.2017.

Research output: Contribution to journalArticle

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