Title: Efficiency and Forward Voltage of Blue and Green Lateral LEDs with V-shaped Defects and Random Alloy Fluctuation in Quantum Wells

Abstract

For nitride-based blue and green light-emitting diodes (LEDs), the forward voltage V_for is larger than expected, especially for green LEDs. This is mainly due to the large barriers to vertical carrier transport caused by the total polarization discontinuity at multiple quantum well and quantum barrier interfaces. The natural random alloy fluctuation in quantum wells has proven to be an important factor reducing V_for. However, this does not suffice in the case of green LEDs because of their larger polarization-induced barrier. V-shaped defects (V-defects) have been proposed as another key factor in reducing V_for to allow lateral injection into multiple quantum wells, thus bypassing the multiple energy barriers incurred by vertical transport. In this paper, to model carrier transport in the whole LED, we consider both random-alloy and V-defect effects. A fully two-dimensional drift-diffusion charge-control solver is used to model both effects. The results indicate that the turn-on voltages for blue and green LEDs are both affected by random alloy fluctuations and the V-defect density. For green LEDs, V_for decreases more due to V-defects, where the smaller polarization barrier at the V-defect sidewall is the major path for lateral carrier injection. Then, we discuss how the V-defect density and size affectsmore » the results.« less

Authors:

Ho, Cheng-Han ^[1]; Speck, James S. ^[2]; Weisbuch, Claude ^[3]; Wu, Yuh-Renn  ^[4]

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+ Show Author Affiliations

1. National Taiwan University, Taipei (Taiwan)
2. University of California, Santa Barbara, CA (United States)
3. University of California, Santa Barbara, CA (United States); Centre de Recherche en Gestion - Ecole Polytechnique / CNRS, Palaiseau (France)
4. National Taiwan University, Taipei (Taiwan); Industrial Technology Research Laboratories, Hsinchu (Taiwan)

Publication Date:

Tue Jan 25 00:00:00 EST 2022

Research Org.:

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

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE); Ministry of Science and Technology, Taiwan; National Science Foundation (NSF); Simons Foundation; French Agence Nationale de la Re-cherche (ANR)

OSTI Identifier:

1979642

Grant/Contract Number:  

EE0009691; MOST 108-2628-E-002- 010-MY3; MOST 110-2923-E-002-002; MOST 111- 2923-E-002-009; DMS-1839077; 601952; 601954; ANR-20-CE05-0037-01

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review Applied

Additional Journal Information:

Journal Volume: 17; Journal Issue: 1; 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; carrier dynamics; carrier generation and recombination; classical transport; optoelectronics; disordered alloys; III-V semiconductors; LEDs: quantum wells