Thermal stability of thin InGaN films on GaN

• Published in: Journal of crystal growth Vol. 312; no. 11; pp. 1817 - 1822
• Main Authors: Thaler, G.T., Koleske, D.D., Lee, S.R., Bogart, K.H.A., Crawford, M.H.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-05-2010; Elsevier
• Subjects: A1. Decomposition; A1. Photoluminescence; A1. X-ray diffraction; A2. Metalorganic chemical vapor deposition; Annealing; B1. Nitrides; B3. Light-emitting diodes; Concentration (composition); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Decomposition; Exact sciences and technology; Gallium nitrides; Indium; Indium gallium nitrides; Materials science; Methods of crystal growth; physics of crystal growth; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Photoluminescence; Physics; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; Thermal expansion; thermomechanical effects and density; Thermal properties of condensed matter; Thermal properties of crystalline solids; Thermal stability; Thin films; A1. Decomposition; A2. Metalorganic chemical vapor deposition; B1. Nitrides; A1. X-ray diffraction; B3. Light-emitting diodes; A1. Photoluminescence; Gallium; Luminescence; Photoluminescence; XRD; Gallium nitride; Thermal stability; Thin films; Optical properties; Reaction mechanism; Indium nitride; Activation energy; Temperature dependence; Thick films; Light emitting diodes; Optoelectronic devices; Indium; MOCVD; III-V compound; Thermal properties; Quench defect; Growth mechanism; III-V semiconductors
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2010.03.008

The thermal stability of ∼200-nm-thick InGaN thin films on GaN was investigated using isothermal and isochronal post-growth anneals. The In
x
Ga
1−
x
N films (
x=0.08–0.18) were annealed in N
2 at 600–1000
°C for 15–60
min, and the resulting film degradation was monitored using X-ray diffraction (XRD) and photoluminescence (PL) measurements. As expected, films with higher indium concentration showed more evidence for decomposition than the samples with lower indium concentration. Also for each alloy composition, decreases in the PL intensity were observed starting at much lower temperatures compared to decreases in the XRD intensity. This difference in sensitivity of the PL and XRD techniques to the InGaN decomposition suggest that defects that quench luminescence are generated prior to the onset of structural decomposition. For the higher indium concentration films, the bulk decomposition proceeds by forming metallic indium and gallium regions as observed by XRD. For the 18% indium concentration film, measurement of the temperature-dependent InGaN decomposition yields an activation energy,
E
A
, of 0.87±0.07
eV, which is similar to the
E
A
for bulk InN decomposition. The InGaN integrated XRD signal of the 18% film displays an exponential decrease vs. time, implying InGaN decomposition proceeds via a first-order reaction mechanism.