skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Controlled Electron Leakage in Electron Blocking Layer Free InGaN/GaN Nanowire Light-Emitting Diodes
In this study, we have proposed and investigated the effect of coupled quantum wells to reduce electron overflow in InGaN/GaN nanowire white color light-emitting diodes. The coupled quantum well before the active region could decrease the thermal velocity, which leads to a reduced electron mean free path. This improves the electron confinement in the active region and mitigates electron overflow in the devices. In addition, coupled quantum well after the active region utilizes the leaked electrons from the active region and contributes to the white light emission. Therefore, the output power and external quantum efficiency of the proposed nanowire LEDs are improved. Moreover, the efficiency droop was negligible up to 900 mA injection current.  more » « less
Award ID(s):
2013780
PAR ID:
10312316
Author(s) / Creator(s):
Date Published:
Journal Name:
Facta Universitatis
Volume:
34
Issue:
3
ISSN:
0352-9665
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; ; (, Optical Materials Express)
    We report on the illustration of the first electron blocking layer (EBL) free AlInN nanowire light-emitting diodes (LEDs) operating in the deep ultraviolet (DUV) wavelength region (sub-250 nm). We have systematically analyzed the results using APSYS software and compared with simulated AlGaN nanowire DUV LEDs. From the simulation results, significant efficiency droop was observed in AlGaN based devices, attributed to the significant electron leakage. However, compared to AlGaN nanowire DUV LEDs at similar emission wavelength, the proposed single quantum well (SQW) AlInN based light-emitters offer higher internal quantum efficiency without droop up to current density of 1500 A/cm2and high output optical power. Moreover, we find that transverse magnetic polarized emission is ∼ 5 orders stronger than transverse electric polarized emission at 238 nm wavelength. Further research shows that the performance of the AlInN DUV nanowire LEDs decreases with multiple QWs in the active region due to the presence of the non-uniform carrier distribution in the active region. This study provides important insights on the design of new type of high performance AlInN nanowire DUV LEDs, by replacing currently used AlGaN semiconductors. 
    more » « less
  2. ; ; ; ; (, Micromachines)
    null (Ed.)
    To prevent electron leakage in deep ultraviolet (UV) AlGaN light-emitting diodes (LEDs), Al-rich p-type AlxGa(1−x)N electron blocking layer (EBL) has been utilized. However, the conventional EBL can mitigate the electron overflow only up to some extent and adversely, holes are depleted in the EBL due to the formation of positive sheet polarization charges at the heterointerface of the last quantum barrier (QB)/EBL. Subsequently, the hole injection efficiency of the LED is severely limited. In this regard, we propose an EBL-free AlGaN deep UV LED structure using graded staircase quantum barriers (GSQBs) instead of conventional QBs without affecting the hole injection efficiency. The reported structure exhibits significantly reduced thermal velocity and mean free path of electrons in the active region, thus greatly confines the electrons over there and tremendously decreases the electron leakage into the p-region. Moreover, such specially designed QBs reduce the quantum-confined Stark effect in the active region, thereby improves the electron and hole wavefunctions overlap. As a result, both the internal quantum efficiency and output power of the GSQB structure are ~2.13 times higher than the conventional structure at 60 mA. Importantly, our proposed structure exhibits only ~20.68% efficiency droop during 0–60 mA injection current, which is significantly lower compared to the regular structure. 
    more » « less
  3. ; ; ; ; (, International Journal of Numerical Modelling: Electronic Networks, Devices and Fields)
    Abstract In this work, an electron blocking layer (EBL) free light emitting diode (LED) nanowire is proposed with alternate prestrained layers of InxGa1−xN/GaN, which are inserted between the GaN/InGaN multi‐quantum wells (MQWs) and n‐GaN layer. This study signifies the role of prestrained layers on the piezoelectric polarization of LED nanowires, for enhanced luminescence. When compared with the conventional one, the EBL free LED nanowire with prestrained layer shows an enhancement of ~2.897% efficiency, which occurs due to the reduction of polarization field in the active region. The LED with 15% indium in the prestrained layer obtains a maximum efficiency of 85.21% along with a minimum efficiency droop of 3.848% at 40 mA injected current. The proposed III‐nitride LED nanostructure allows for achieving superior optical power across the output spectral range. 
    more » « less
  4. ; ; (, 2022 Compound Semiconductor Week)
    We report on the demonstration of electron blocking layer free AlInN nanowire light-emitting diodes (LEDs) operating in the 280–365 nm wavelength region. The molecular beam epitaxial grown AlInN nanowires have a relatively high internal quantum efficiency of > 52%. Moreover, we show that the light extraction efficiency of the nanowires could reach ~ 63% for hexagonal photonic crystal nanowire structures which is significantly higher compared to that of the random nanowire arrays. This study provides significant insights into the design and fabrication of a new type of high-performance AlInN nanowire ultraviolet light-emitters. 
    more » « less
  5. ; ; ; ; ; (, Journal of Nanophotonics)
    We present our study on AlInN-based ultraviolet (UV) core-shell nanowire light-emitting diodes (LEDs) utilizing a polarization-induced doping technique. Due to the formation of a core-shell structure, the non-radiative recombination on the nanowire surface is significantly reduced. Moreover, we have successfully fabricated AlInN/GaN-based core-shell nanowire UV LED employing polarization-engineered quantum barriers instead of conventional structures. The LED device exhibits significantly improved carrier concentration in the active region and decreased electron leakage due to the gradually raised effective conduction band barrier heights. At room temperature, the AlInN LEDs exhibit strong and stable emission at 296 nm. We provide a promising approach to fabricating high-performance light emitters. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email