Raman, EPD, XRD, and TEM analysis of GaN on commercial patterned-sapphire substrates  (Conference Presentation)

Vin-Cent Su; Po-Hsun Chen; Shang-Hsuan Wu; Chieh-Hsiung Kuan

doi:10.1117/12.2292079

14 March 2018 Raman, EPD, XRD, and TEM analysis of GaN on commercial patterned-sapphire substrates (Conference Presentation)

Vin-Cent Su, Po-Hsun Chen, Shang-Hsuan Wu, Chieh-Hsiung Kuan

Author Affiliations +

Proceedings Volume 10554, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XXII; 105540C (2018) https://doi.org/10.1117/12.2292079
Event: SPIE OPTO, 2018, San Francisco, California, United States

Abstract

Despite of only having 25 years so far, the efficiency of GaN-based light-emitting diodes (LEDs) has multiplied many times, which has been able to produce six times more efficiency than traditional incandescent light bulbs. As the great prospect of next-generation solid-state lighting, their external-quantum efficiency (EQE) still requires further improvement. Currently, the single growth method by patterned-sapphire substrates (PSSs) can not only improve internal-quantum efficiency (IQE) but also enhance light-extraction efficiency (LEE). However, few paper reports the epitaxial critical point for GaN on commercial PSSs, at which residual strain starts relaxing along with defect generation in epitaxial film. In this work, a complete study on material properties of GaN on the commercial PSS is reported through the use of Raman, etch pit density (EPD), XRD and TEM. We demonstrate that the accuracy of Raman measurement is pretty good. Edge- and screw-mixed threading dislocations measured with EPD are strongly correlated to E2-high and A1-LO’s FWHM of the Raman method, respectively. The XRD-measured lattice constants can be calculated through the Raman shift of E2-high and A1-LO, individually. Through the investigation of TEM, the increase in the 3D growth of GaN on the commercial PSS accumulates residual strain inside it, followed by strain saturation in GaN when it approaches to the 2D growth. After reaching the summit of residual strain inside GaN, called the epitaxial critical point, it starts releasing strain in it and forcefully bends threading dislocation to the surface of the commercial PSS.

Conference Presentation

Citation Download Citation

Vin-Cent Su, Po-Hsun Chen, Shang-Hsuan Wu, and Chieh-Hsiung Kuan "Raman, EPD, XRD, and TEM analysis of GaN on commercial patterned-sapphire substrates (Conference Presentation)", Proc. SPIE 10554, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XXII, 105540C (14 March 2018); https://doi.org/10.1117/12.2292079

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
PRESENTATION

WATCH
PRESENTATION SAVE TO MY LIBRARY

GET CITATION

KEYWORDS

Gallium nitride

Light emitting diodes

Raman spectroscopy

Transmission electron microscopy

3D metrology

Crystals

External quantum efficiency

Show All Keywords

Keywords/Phrases

Search In:

Publication Years