TY - JOUR

T1 - Ultrashort Pulse Laser Lift-Off Processing of InGaN/GaN Light-Emitting Diode Chips

AU - Yulianto, Nursidik

AU - Kadja, Grandprix T.M.

AU - Bornemann, Steffen

AU - Gahlawat, Soniya

AU - Majid, Nurhalis

AU - Triyana, Kuwat

AU - Abdi, Fatwa F.

AU - Wasisto, Hutomo Suryo

AU - Waag, Andreas

N1 - Funding information: This work was funded in part by the Lower Saxony Ministry for Science and Culture (N-MWK) within the group of “LENA-OptoSense”, in part by the European Union’s Horizon 2020 research and innovation program within the project of “ChipScope—Overcoming the Limits of Diffraction with Super-Resolution Lighting on a Chip” under grant agreement no 737089, and in part by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) within “Excellence Strategy of EXC-2123 QuantumFrontiers—390837967”. The authors thank Christoph Margenfeld and Irene Manglano Clavero for GaN wafer preparation in the epitaxy competence center (ec2). Nursidik Yulianto acknowledges the Ministry of Research, Technology and Higher Education of the Republic of Indonesia (RISTEKDIKTI) for the Ph.D. scholarship of RISET-Pro under no. 345/RISET-Pro/FGS/VIII/2016, and the Indonesian-German Centre for Nano and Quantum Technologies (IG-Nano) for the support. Soniya Gahlawat acknowledges DAAD (Deutscher Akademischer Austauschdienst) for the financial support provided during this work with the funding programme, Research Grants - Bi-nationally Supervised Doctoral Degrees, 2019/20. The authors thank Angelika Schmidt, Juliane Breitfelder, and Aileen Michalski for their technical support during the experiments, as well as Prof. Winfried Daum for providing AFM tool.

PY - 2021/2/23

Y1 - 2021/2/23

N2 - 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).

AB - 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).

KW - chip integration

KW - femtosecond laser

KW - gallium nitride

KW - laser lift-off

KW - laser micromachining

KW - LED

UR - http://www.scopus.com/inward/record.url?scp=85100240965&partnerID=8YFLogxK

U2 - 10.1021/acsaelm.0c00913

DO - 10.1021/acsaelm.0c00913

M3 - Article

AN - SCOPUS:85100240965

VL - 3

SP - 778

EP - 788

JO - ACS Applied Electronic Materials

JF - ACS Applied Electronic Materials

IS - 2

ER -