Microfabrication in free-standing gallium nitride using UV laser micromachining

E. Gu, H. Howard, A. Conneely, G.M. O'Connor, E.K. Illy, M.R.H. Knowles, P.R. Edwards, R.W. Martin, I.M. Watson, M.D. Dawson

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Gallium nitride (GaN) and related alloys are important semiconductor materials for fabricating novel photonic devices such as ultraviolet (UV) light-emitting diodes (LEDs) and vertical cavity surface-emitting lasers (VCSELs). Recent technical advances have made free-standing GaN substrates available and affordable. However, these materials are strongly resistant to wet chemical etching and also, low etch rates restrict the use of dry etching. Thus, to develop alternative high-resolution processing for these materials is increasingly important. In this paper, we report the fabrication of microstructures in free-standing GaN using pulsed UV lasers. An effective method was first developed to remove the re-deposited materials due to the laser machining. In order to achieve controllable machining and high resolution in GaN, machining parameters were carefully optimised. Under the optimised conditions, precision features such as holes (through holes, blind or tapered holes) on a tens of micrometer length scale have been machined. To fabricate micro-trenches in GaN with vertical sidewalls and a flat bottom, different process strategies of laser machining were tested and optimised. Using this technique, we have successfully fabricated high-quality micro-trenches in free-standing GaN with various widths and depths. The approach combining UV laser micromachining and other processes is also discussed. Our results demonstrate that the pulsed UV laser is a powerful tool for fabricating precision microstructures and devices in gallium nitride.
LanguageEnglish
Pages4897-4901
Number of pages5
JournalApplied Surface Science
Volume252
Issue number13
DOIs
Publication statusPublished - 2006

Fingerprint

Ultraviolet lasers
Gallium nitride
Microfabrication
Micromachining
Machining
Pulsed lasers
Photonic devices
Microstructure
Dry etching
Wet etching
Lasers
Surface emitting lasers
gallium nitride
Light emitting diodes
Semiconductor materials
Fabrication
Substrates
Processing

Keywords

  • gallium nitride
  • pulsed UV lasers
  • micromachining
  • lasers
  • photonics

Cite this

Gu, E. ; Howard, H. ; Conneely, A. ; O'Connor, G.M. ; Illy, E.K. ; Knowles, M.R.H. ; Edwards, P.R. ; Martin, R.W. ; Watson, I.M. ; Dawson, M.D. / Microfabrication in free-standing gallium nitride using UV laser micromachining. In: Applied Surface Science. 2006 ; Vol. 252, No. 13. pp. 4897-4901.
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Microfabrication in free-standing gallium nitride using UV laser micromachining. / Gu, E.; Howard, H.; Conneely, A.; O'Connor, G.M.; Illy, E.K.; Knowles, M.R.H.; Edwards, P.R.; Martin, R.W.; Watson, I.M.; Dawson, M.D.

In: Applied Surface Science, Vol. 252, No. 13, 2006, p. 4897-4901.

Research output: Contribution to journalArticle

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T1 - Microfabrication in free-standing gallium nitride using UV laser micromachining

AU - Gu, E.

AU - Howard, H.

AU - Conneely, A.

AU - O'Connor, G.M.

AU - Illy, E.K.

AU - Knowles, M.R.H.

AU - Edwards, P.R.

AU - Martin, R.W.

AU - Watson, I.M.

AU - Dawson, M.D.

N1 - Also available as a conference paper at http://strathprints.strath.ac.uk/9039/

PY - 2006

Y1 - 2006

N2 - Gallium nitride (GaN) and related alloys are important semiconductor materials for fabricating novel photonic devices such as ultraviolet (UV) light-emitting diodes (LEDs) and vertical cavity surface-emitting lasers (VCSELs). Recent technical advances have made free-standing GaN substrates available and affordable. However, these materials are strongly resistant to wet chemical etching and also, low etch rates restrict the use of dry etching. Thus, to develop alternative high-resolution processing for these materials is increasingly important. In this paper, we report the fabrication of microstructures in free-standing GaN using pulsed UV lasers. An effective method was first developed to remove the re-deposited materials due to the laser machining. In order to achieve controllable machining and high resolution in GaN, machining parameters were carefully optimised. Under the optimised conditions, precision features such as holes (through holes, blind or tapered holes) on a tens of micrometer length scale have been machined. To fabricate micro-trenches in GaN with vertical sidewalls and a flat bottom, different process strategies of laser machining were tested and optimised. Using this technique, we have successfully fabricated high-quality micro-trenches in free-standing GaN with various widths and depths. The approach combining UV laser micromachining and other processes is also discussed. Our results demonstrate that the pulsed UV laser is a powerful tool for fabricating precision microstructures and devices in gallium nitride.

AB - Gallium nitride (GaN) and related alloys are important semiconductor materials for fabricating novel photonic devices such as ultraviolet (UV) light-emitting diodes (LEDs) and vertical cavity surface-emitting lasers (VCSELs). Recent technical advances have made free-standing GaN substrates available and affordable. However, these materials are strongly resistant to wet chemical etching and also, low etch rates restrict the use of dry etching. Thus, to develop alternative high-resolution processing for these materials is increasingly important. In this paper, we report the fabrication of microstructures in free-standing GaN using pulsed UV lasers. An effective method was first developed to remove the re-deposited materials due to the laser machining. In order to achieve controllable machining and high resolution in GaN, machining parameters were carefully optimised. Under the optimised conditions, precision features such as holes (through holes, blind or tapered holes) on a tens of micrometer length scale have been machined. To fabricate micro-trenches in GaN with vertical sidewalls and a flat bottom, different process strategies of laser machining were tested and optimised. Using this technique, we have successfully fabricated high-quality micro-trenches in free-standing GaN with various widths and depths. The approach combining UV laser micromachining and other processes is also discussed. Our results demonstrate that the pulsed UV laser is a powerful tool for fabricating precision microstructures and devices in gallium nitride.

KW - gallium nitride

KW - pulsed UV lasers

KW - micromachining

KW - lasers

KW - photonics

UR - http://www.ucg.ie/faculties_departments/physics/ncla/publications/GaN%20Laser%20micromachining.pdf

UR - http://dx.doi.org/10.1016/j.apsusc.2005.07.117

U2 - 10.1016/j.apsusc.2005.07.117

DO - 10.1016/j.apsusc.2005.07.117

M3 - Article

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EP - 4901

JO - Applied Surface Science

T2 - Applied Surface Science

JF - Applied Surface Science

SN - 0169-4332

IS - 13

ER -