Ultrashort Pulse Laser Lift-Off Processing of InGaN/GaN Light-Emitting Diode Chips

verfasst von
Nursidik Yulianto, Grandprix T.M. Kadja, Steffen Bornemann, Soniya Gahlawat, Nurhalis Majid, Kuwat Triyana, Fatwa F. Abdi, Hutomo Suryo Wasisto, Andreas Waag
Abstract

Gallium nitride (GaN) film delamination is an important process during the fabrication of GaN light-emitting diodes (LEDs) and laser diodes. Here, we utilize 520 nm femtosecond laser pulses, exploiting nonlinear absorption rather than single-photon absorption such as in conventional laser lift-off (LLO) employing excimer or Q-switched laser sources. The focus of this study is to investigate the influence of laser scanning speed and integrated fluence corresponding to laser energy per area during the LLO processing of GaN LED chips and their resulting structural properties. Because both the sapphire substrate and InGaN/GaN heterostructures are fully transparent to the emission of the laser system, a key question is related to the impact of laser pulses on the quality of a thin film structure. Therefore, several characterization methods (i.e., scanning electron microscopy, atomic force microscopy, X-ray diffraction, Raman spectroscopy, and electroluminescence spectroscopy) were employed to understand the material modifications made by femtosecond LLO (fs-LLO). We demonstrated that by adjusting the laser scanning speed, smooth GaN surfaces and good crystal quality could be obtained regardless of the existing delamination of metal contact, which then slightly downgraded the LED performance. Here, the integrated fluence level was set in the range of 2.6-4.4 J/cm2 to enable the fs-LLO process. Moreover, two mitigation strategies were developed and proven to improve the optoelectrical characteristics of the lifted-off LEDs (i.e., modification of the processing step related to the metal creation and reduction of laser energy).

Externe Organisation(en)
Technische Universität Braunschweig
Lembaga Ilmu Pengetahuan Indonesia
Institut Teknologi Bandung (ITB)
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH
Indian Institute of Technology Delhi (IITD)
Technische Universität Clausthal
Gadjah Mada University
Typ
Artikel
Journal
ACS Applied Electronic Materials
Band
3
Seiten
778-788
Anzahl der Seiten
11
Publikationsdatum
23.02.2021
Publikationsstatus
Veröffentlicht
Peer-reviewed
Ja
ASJC Scopus Sachgebiete
Elektronische, optische und magnetische Materialien, Elektrochemie, Werkstoffchemie
Elektronische Version(en)
https://doi.org/10.1021/acsaelm.0c00913 (Zugang: Geschlossen)