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

Abstract

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.

Authors:

Lynsky, Cheyenne  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-6895-9125"

Lheureux, Guillaume ^[1]; Bonef, Bastien ^[1]; Qwah, Kai Shek ^[1]; White, Ryan C. ^[1]; DenBaars, Steven P. ^[1]; Nakamura, Shuji  ^[1];

• Search DOE PAGES for author "Nakamura, Shuji"
• Search DOE PAGES for ORCID "0000-0001-6334-2428"

Wu, Yuh-Renn ^[2]; Weisbuch, Claude ^[3]; Speck, James S. ^[1]

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+ Show Author Affiliations

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

Publication Date:

Tue May 31 00:00:00 EDT 2022

Research Org.:

Univ. of California, Santa Barbara, CA (United States)

Sponsoring Org.:

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)

OSTI Identifier:

1979649

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

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review Applied

Additional Journal Information:

Journal Volume: 17; Journal Issue: 5; Journal ID: ISSN 2331-7019

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

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