Characteristics comparison between GaN epilayers grown on patterned and unpatterned sapphire substrate (0 0 0 1)

Jae Chul Song, Seon Ho Lee, In-Hwan Lee, Kyeong Won Seol, Santhakumar Kannappan, Cheul Ro Lee

Research output: Contribution to journalArticle

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Abstract

GaN epilayers were grown on lens-shaped-pattern sapphire substrate (PSS) (0 0 0 1) and unpatterned sapphire substrate (UPSS) (0 0 0 1) by metal-organic chemical vapor deposition (MOCVD). The quality of the grown GaN epilayers on the PSS and UPSS were compared. Structural characteristics, surface morphology and optical properties of the GaN epilayers were investigated using double crystal X-ray diffraction (DCXRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and photoluminescence (PL). A lens-shaped pattern was formed on the sapphire substrate to reduce threading dislocation (TD) density and also to improve the optical emission efficiency by internal reflection on the lens. SEM images show the growth of GaN epilayers at various times. Full coalescence is observed at a growth time of 80 min. It is seen from the DCXRD rocking spectrum that full width at half maximum (FWHM) of the GaN grown on PSS was 438.7 arcsec which is less than UPSS value. The lower value of FWHM indicates that the crystalline quality of the GaN epilayers grown on PSS is improved compared to GaN grown on UPSS. It is clearly seen from the AFM images that the dislocation density is less for the GaN grown on PSS. A strong and sharp PL band edge emission was observed for the GaN grown on PSS compared to UPSS. Defect related yellow luminescence was observed for GaN grown on UPSS which did not appear for PSS. The FWHM at the 364.3 nm peak position was evaluated to be 50.7 meV from the PL spectra for GaN grown on PSS. The above result indicates GaN epilayers can be grown on PSS with low TD density and will be useful for optical emission.

Original languageEnglish
Pages (from-to)321-324
Number of pages4
JournalJournal of Crystal Growth
Volume308
Issue number2
DOIs
Publication statusPublished - 2007 Oct 15
Externally publishedYes

Fingerprint

Aluminum Oxide
Epilayers
Sapphire
sapphire
Substrates
Full width at half maximum
Lenses
Photoluminescence
lenses
photoluminescence
light emission
Atomic force microscopy
atomic force microscopy
Organic Chemicals
X ray diffraction
Crystals
Scanning electron microscopy
scanning electron microscopy
Organic chemicals
Coalescence

Keywords

  • A1. Optical reflectance
  • A1. Threading dislocation
  • A3. Metal-organic chemical vapor deposition (MOCVD)
  • B1. GaN
  • B1. Patterned sapphire substrate

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Inorganic Chemistry
  • Materials Chemistry

Cite this

Characteristics comparison between GaN epilayers grown on patterned and unpatterned sapphire substrate (0 0 0 1). / Song, Jae Chul; Lee, Seon Ho; Lee, In-Hwan; Seol, Kyeong Won; Kannappan, Santhakumar; Lee, Cheul Ro.

In: Journal of Crystal Growth, Vol. 308, No. 2, 15.10.2007, p. 321-324.

Research output: Contribution to journalArticle

Song, Jae Chul ; Lee, Seon Ho ; Lee, In-Hwan ; Seol, Kyeong Won ; Kannappan, Santhakumar ; Lee, Cheul Ro. / Characteristics comparison between GaN epilayers grown on patterned and unpatterned sapphire substrate (0 0 0 1). In: Journal of Crystal Growth. 2007 ; Vol. 308, No. 2. pp. 321-324.
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T1 - Characteristics comparison between GaN epilayers grown on patterned and unpatterned sapphire substrate (0 0 0 1)

AU - Song, Jae Chul

AU - Lee, Seon Ho

AU - Lee, In-Hwan

AU - Seol, Kyeong Won

AU - Kannappan, Santhakumar

AU - Lee, Cheul Ro

PY - 2007/10/15

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N2 - GaN epilayers were grown on lens-shaped-pattern sapphire substrate (PSS) (0 0 0 1) and unpatterned sapphire substrate (UPSS) (0 0 0 1) by metal-organic chemical vapor deposition (MOCVD). The quality of the grown GaN epilayers on the PSS and UPSS were compared. Structural characteristics, surface morphology and optical properties of the GaN epilayers were investigated using double crystal X-ray diffraction (DCXRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and photoluminescence (PL). A lens-shaped pattern was formed on the sapphire substrate to reduce threading dislocation (TD) density and also to improve the optical emission efficiency by internal reflection on the lens. SEM images show the growth of GaN epilayers at various times. Full coalescence is observed at a growth time of 80 min. It is seen from the DCXRD rocking spectrum that full width at half maximum (FWHM) of the GaN grown on PSS was 438.7 arcsec which is less than UPSS value. The lower value of FWHM indicates that the crystalline quality of the GaN epilayers grown on PSS is improved compared to GaN grown on UPSS. It is clearly seen from the AFM images that the dislocation density is less for the GaN grown on PSS. A strong and sharp PL band edge emission was observed for the GaN grown on PSS compared to UPSS. Defect related yellow luminescence was observed for GaN grown on UPSS which did not appear for PSS. The FWHM at the 364.3 nm peak position was evaluated to be 50.7 meV from the PL spectra for GaN grown on PSS. The above result indicates GaN epilayers can be grown on PSS with low TD density and will be useful for optical emission.

AB - GaN epilayers were grown on lens-shaped-pattern sapphire substrate (PSS) (0 0 0 1) and unpatterned sapphire substrate (UPSS) (0 0 0 1) by metal-organic chemical vapor deposition (MOCVD). The quality of the grown GaN epilayers on the PSS and UPSS were compared. Structural characteristics, surface morphology and optical properties of the GaN epilayers were investigated using double crystal X-ray diffraction (DCXRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and photoluminescence (PL). A lens-shaped pattern was formed on the sapphire substrate to reduce threading dislocation (TD) density and also to improve the optical emission efficiency by internal reflection on the lens. SEM images show the growth of GaN epilayers at various times. Full coalescence is observed at a growth time of 80 min. It is seen from the DCXRD rocking spectrum that full width at half maximum (FWHM) of the GaN grown on PSS was 438.7 arcsec which is less than UPSS value. The lower value of FWHM indicates that the crystalline quality of the GaN epilayers grown on PSS is improved compared to GaN grown on UPSS. It is clearly seen from the AFM images that the dislocation density is less for the GaN grown on PSS. A strong and sharp PL band edge emission was observed for the GaN grown on PSS compared to UPSS. Defect related yellow luminescence was observed for GaN grown on UPSS which did not appear for PSS. The FWHM at the 364.3 nm peak position was evaluated to be 50.7 meV from the PL spectra for GaN grown on PSS. The above result indicates GaN epilayers can be grown on PSS with low TD density and will be useful for optical emission.

KW - A1. Optical reflectance

KW - A1. Threading dislocation

KW - A3. Metal-organic chemical vapor deposition (MOCVD)

KW - B1. GaN

KW - B1. Patterned sapphire substrate

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