High Efficiency InGaN LEDs Emitting in Green, Amber and Beyond (Final Report)
- The Ohio State Univ., Columbus, OH (United States)
- Case Western Reserve Univ., Cleveland, OH (United States)
This project focuses on developing high efficiency light emitting diodes (LEDs) with green, amber, and longer wavelengths using two compatible material systems based on III-nitride and II-IV-nitride semiconductor heterostructures. The proposed approach uses low-indium-content InGaN and ZnGeN2 or ZnSnN2 heterostructure quantum wells (QWs) as the active regions for high efficiency green and amber LEDs, and therefore to advance high efficiency color-mixed white LED technology. This approach takes advantage of the increased flexibility, afforded by the incorporation of the II-IV-nitrides into the III-nitride layers, to tune the QW active region to lower the emission wavelengths and to increase the electron-hole wave function overlap. This strategy paves a new way to extend the InGaN QW LED emission wavelength without using high-indium-content InGaN. An industrially preferable metalorganic chemical vapor deposition (MOCVD) method was used to develop the growth of ZnGeN2 and ZnSnN2 that are compatible with the InGaN growth. The unique dual chamber MOCVD instrument at OSU was used in this project. This program created an opportunity for the two institutions (The Ohio State University and Case Western Reserve University) with complementary expertise to perform this work. Two graduate students (Md Rezaul Karim (OSU) and Benthara Hewage Dinushi Jayatunga (CWRU)) gained experience in MOCVD growth and various characterization methods including scanning electron microscopy, x-ray diffraction spectroscopy, x-ray photoemission spectroscopy, Hall measurements, cathodoluminescence and photoluminescence. Both students successfully defended their PhD dissertations in April/May 2021. Both Karim and Jayatunga have joined Intel as engineers in June/July 2021. Another two graduate students Kaitian Zhang (OSU) and Chenxi Hu (CWRU) joined the project team since spring 2021 to continue on this project. They were trained on MOCVD epitaxy of InGaN QWs and materials characterization including SEM, AFM, PL, CL, XRD, Hall measurements and electroluminescence. A third student, Vijay Gopal Thirupakuzi Vangipuram (OSU), who joined the group in fall 2021 to perform LED fabrication and characterization. The key research accomplishments of the project include: (1) Successful development of MOCVD epitaxy of single crystalline ZnGeN2 and ZnSnN2. MOCVD growth parameters that determine the stoichiometry of ZnGeN2 and ZnSnN2 films were identified. (2) Experimentally determined the band offsets between GaN/ZnGeN2 and GaN/ZnGaSnN2 hetero-interfaces, which agree very well with the theoretical predictions. (3) Demonstrated the incorporation of thin ZnGeN2 layer in InGaN QWs. Proof-of-concept of the InGaN-ZnGeN2 QW design demonstrated as much as 80 nm of red shift without increasing In composition or QW thickness. (4) InGaN/ZnGeN2 QWs emitting at 480 nm achieved IQE of 47%. Resulted from this project, 7 journal articles were published, and 9 conference papers were presented.
- Research Organization:
- The Ohio State Univ., Columbus, OH (United States); Case Western Reserve Univ., Cleveland, OH (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE)
- DOE Contract Number:
- EE0008718
- OSTI ID:
- 1893918
- Report Number(s):
- DOE-OSU-EE0008718
- Country of Publication:
- United States
- Language:
- English
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