InGaN/GaN Multiple Quantum Well Blue Light Emitting Diodes with Transparent Ni/ITO and Pt/ITO p-Type Contacts
InGaN/GaN multiple quantum wells (MQWs) light-emitting diodes (LEDs) with Ni/ITO (5/50 nm) and Pt/ITO (0.8/50 nm) current spreading layer were investigated. The electrical and optical properties of Ni/ITO and Pt/ITO films were also investigated. It was found that the normalized transmittance of Ni/ITO and Pt/ITO films could reach 79.22 and 78.98% at 460 nm, which was almost equal. It was also found that Pt/ITO had showed better linear current–voltage characteristics compared to Ni/ITO contacts. The specific contact resistance for Pt/ITO contacts was 5.88 × 10−2 Ω cm2, while for Ni/ITO contacts, it was 5.66 × 10−1 Ω cm2 i.e. ~10 time more. The EL intensity of blue LED was much higher with Pt/ITO p-contact compared to Ni/ITO p-contact. The forward voltages (VF) of LEDs for two contacts (Ni/ITO and Pt/ITO p-contacts) at 20 mA current injection were found 4.49 and 3.5 V, respectively.
This work was supported by council of scientific and industrial research (CSIR) under network programme (PSC-0102).
- 2.S.P. DenBaars, D. Feezell, K. Kelchner, S. Pimputkar, C.-C. Pan, C.-C. Yen, S. Tanaka, Y. Zhao, N. Pfaff, R. Farrell, M. Iza, S. Keller, U. Mishra, J.S. Speck, S. Nakamura, Development of gallium-nitride-based light-emitting diodes (LEDs) and laser diodes for energy-efficient lighting and displays. Acta Mater. 61, 945–951 (2013)CrossRefGoogle Scholar
- 3.Y. Kuwahara, T. Fujji, T. Sugiyama, D. Iida, Y. Isobe, Y. Fujjiyama, Y. Morita, M. Iwaya, T. Takeuchi, S. Kamiyama, I. Akasaki, H. Amano, GaInN/GaInN-based solar cells using strained layer GaInN/GaInN superlat tice active layer on free standing GaN substrate. Appl. Phys. Express 4, 021001 (2011)ADSCrossRefGoogle Scholar
- 8.J.-Y. Huang, G.-H. Fan, S.-W. Zheng, Q.-L. Ni, S.-T. Li, J.-X. Cao, S. Jun, Y. Zhang, Improvement of the light output and contact resistance of InGaN-based light-emitting diodes based on tantalum-doped indium tin oxide as p-type electrodes. Chin. Phys. B 19(4), 047205-1–047205-4 (2010)ADSGoogle Scholar