1887
banner image
No data available.
Please log in to see this content.
You have no subscription access to this content.
No metrics data to plot.
The attempt to load metrics for this article has failed.
The attempt to plot a graph for these metrics has failed.
Improvement of light extraction from high-power flip-chip light-emitting diodes by femtosecond laser direct structuring of the sapphire backside surface
Rent:
Rent this article for
USD
10.1063/1.2981203
/content/aip/journal/jap/104/7/10.1063/1.2981203
http://aip.metastore.ingenta.com/content/aip/journal/jap/104/7/10.1063/1.2981203
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

(a) Sketch of a high-power flip-chip LED and (b) optical microscope image of the flip-chip LED mounted on a PCB by chip-on-board technology. The base point (0,0) is a benchmark for an Cartesian coordinate system, which defines the coordinates and the orientation of the inscribed structure. The quarters , , , and and the white lines define the individual structures and directions the optical cross sections on the light intensity distributions were recorded from (compare also Fig. 9).

Image of FIG. 2.
FIG. 2.

Schematic of the experimental setup for the femtosecond laser direct structuring of the backside surface of the flip-chip LEDs. Groove lines are fabricated by an irradiation of the backside surfaces of the flip-chip LEDs with femtosecond laser pulses and a contemporaneous motion of the translation stage the LEDs are fixed on with a specific scanning velocity.

Image of FIG. 3.
FIG. 3.

Optical microscope image of the test lines fabricated by femtosecond laser ablation on the backside surface of the sapphire substrate of a flip-chip LED. The lines were inscribed with laser powers varying from 120 to with an increment of , (from top to bottom) and a constant scanning velocity of . Note that the lowermost line, in turn, was written with the maximal laser power of for a better differentiation of the fabrication area.

Image of FIG. 4.
FIG. 4.

AFM image of the groove lines inscribed on the backside surface of the sapphire substrate of a flip-chip LED with a laser power of and a scanning velocity of .

Image of FIG. 5.
FIG. 5.

3D AFM images of the groove lines inscribed on the backside surfaces of the sapphire substrates of flip-chip LEDs with laser powers of 70 and , respectively.

Image of FIG. 6.
FIG. 6.

AFM height profiles of the inscribed groove lines for laser powers of 70 , 80 , 90 , and .

Image of FIG. 7.
FIG. 7.

Optical output power of a LED measured as a function of the dc forward current before and after (groove lines with a periodicity of were inscribed with a laser power of at a scanning speed of ) femtosecond laser structuring of the sapphire backside surface.

Image of FIG. 8.
FIG. 8.

Enhancement of light extraction from the backside surface of the sapphire substrates vs laser power for groove line fabrication.

Image of FIG. 9.
FIG. 9.

optical sections of the light intensity distribution from a partially structured LED. [see Fig. 1(b)]. (a) Left side: LED area structured with groove lines fabricated with a laser power of . Right side: nonstructured LED area. (b) Left side: LED area structured with groove lines fabricated with a laser power of . Right side: nonstructured LED area. The images were recorded by a confocal technique with a objective lens having a numerical aperture of 0.95. The values of the light intensity are normalized to a linear color spectrum scale, with the highest values represented by a red color and the lowest values by a blue color.

Loading

Article metrics loading...

/content/aip/journal/jap/104/7/10.1063/1.2981203
2008-10-08
2014-04-19
Loading

Full text loading...

This is a required field
Please enter a valid email address
752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Improvement of light extraction from high-power flip-chip light-emitting diodes by femtosecond laser direct structuring of the sapphire backside surface
http://aip.metastore.ingenta.com/content/aip/journal/jap/104/7/10.1063/1.2981203
10.1063/1.2981203
SEARCH_EXPAND_ITEM