Improved Vertical Carrier Transport for Green III-Nitride LEDs Using ( In , Ga ) N Alloy Quantum Barriers

Journal Article · Tue May 31 00:00:00 EDT 2022 · Physical Review Applied

DOI:https://doi.org/10.1103/physrevapplied.17.054048· OSTI ID:1979649

Lynsky, Cheyenne  ^[1]; Lheureux, Guillaume ^[1]; Bonef, Bastien ^[1]; Qwah, Kai Shek ^[1]; White, Ryan C. ^[1]; DenBaars, Steven P. ^[1]; Nakamura, Shuji  ^[1]; Wu, Yuh-Renn ^[2]; Weisbuch, Claude ^[3]; Speck, James S. ^[1]

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1. Univ. of California, Santa Barbara, CA (United States)
2. National Taiwan Univ., Taipei (Taiwan). Graduate Inst. of Photonics and Optoelectronics
3. Univ. of California, Santa Barbara, CA (United States); Ecole Polytechnique, Palaiseau (France). Lab. de Physique de la Matière Condensée

We report on experimental and simulation-based results using $(\mathrm{In},\mathrm{Ga})\mathrm{N}$ alloy quantum barriers in c-plane green light-emitting diode (LED) structures as a means to improve vertical carrier transport and reduce forward voltage $\left(V_F\right)$. Three-dimensional device simulations that include random alloy fluctuations are used to understand carrier behavior in a disordered potential. The simulated current density–voltage (J-V) characteristics and modified electron-hole overlap $|F_{\mathrm{mod}}{|}^2$ indicate that increasing the indium fraction in the $(\mathrm{In},\mathrm{Ga})\mathrm{N}$ quantum barriers leads to a reduced polarization discontinuity at the interface between the quantum barrier and quantum well, thereby reducing $V_F$ and improving $|F_{\mathrm{mod}}{|}^2$. Maps of electron and hole current through the device show a relatively homogenous distribution in the $XY$ plane for structures using $\mathrm{Ga}\mathrm{N}$ quantum barriers; in contrast, preferential pathways for vertical transport are identified in structures with $(\mathrm{In},\mathrm{Ga})\mathrm{N}$ barriers as regions of high and low current. A positive correlation between hole (electron) current in the p-side (n-side) barrier and indium fraction reveals that preferential pathways exist in regions of high indium content. Furthermore, a negative correlation between the strain ${\epsilon }_{zz}$ and indium fraction shows that high indium content regions have reduced strain-induced piezoelectric polarization in the Z direction due to the mechanical constraint of the surrounding lower indium content regions. Experimentally, multiple quantum well green LEDs with $(\mathrm{In},\mathrm{Ga})\mathrm{N}$ quantum barriers exhibit lower $V_F$ and blue-shifted wavelengths relative to LEDs with $\mathrm{Ga}\mathrm{N}$ quantum barriers, consistent with simulation data. These results can be used to inform heterostructure design of low $V_F$, long-wavelength LEDs and provide important insight into the nature of carrier transport in III-nitride alloy materials.

• Research Organization: Univ. of California, Santa Barbara, CA (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE); National Science Foundation (NSF); Simons Foundation; Taiwanese Ministry of Science and Technology (MOST); French Agence Nationale de la Recherche (ANR)
• Grant/Contract Number: EE0008204; DMS-1839077; 601952; 601954; 108-2628-E-002-010-MY3; 111-2923-E-002-009; ANR-20-CE05-0037-01; DMR-1121053
• OSTI ID: 1979649
• Journal Information: Physical Review Applied, Vol. 17, Issue 5; ISSN 2331-7019
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
Physics
localization
optoelectronics
transport phenomena
disordered alloys
III-V semiconductors
LEDs
epitaxy
methods in transport