Development of High Power Green Light Emitting Diode Chips

The development of high emission power green light emitting diodes chips using GaInN/GaN multi quantum well heterostructures on sapphire substrate in our group is being reviewed. We analyze the electronic bandstructure in highly polarized GaInN/GaN quantum wells to identify the appropriate device structures. We describe the optimization of the epitaxial growth for highest device performance. Applying several optimization schemes, we find that lateral smoothness and homogeneity of the active region as characterized by atomic force microscopy is a most telling character of high yield, high output power devices emitting near 525 nm. In un-encapsulated epi-up mounted (400 μm)2 die we achieve 2.5 mW at 20 mA at 525 nm. We describe die performance, wafer yield, and process stability, and reproducibility for our production-scale implementation of this green LED die process.

Download Full-text

A hybrid green light-emitting diode comprised of n-ZnO/(InGaN/GaN) multi-quantum-wells/p-GaN

Applied Physics Letters ◽

10.1063/1.2975165 ◽

2008 ◽

Vol 93 (8) ◽

pp. 081111 ◽

Cited By ~ 52

Author(s):

C. Bayram ◽

F. Hosseini Teherani ◽

D. J. Rogers ◽

M. Razeghi

Keyword(s):

Quantum Wells ◽

Light Emitting Diode ◽

Green Light ◽

Light Emitting

Download Full-text

Colloidal quantum dot active layer electroluminescence in a solid GaN matrix

MRS Proceedings ◽

10.1557/proc-0891-ee03-06 ◽

2005 ◽

Vol 891 ◽

Author(s):

Jennifer Pagan ◽

Edward Stokes ◽

Kinnari Patel ◽

Casey Burkhart ◽

Mike Ahrens

Keyword(s):

Active Layer ◽

Light Emitting Diode ◽

Cdse Quantum Dots ◽

Light Emitting ◽

Force Microscopy ◽

Turn On ◽

Atomic Force ◽

Transmission Line Method ◽

Gan Led ◽

Colloidal Quantum Dot

ABSTRACTIn this paper the preliminary results of incorporating a novel active layer into a GaN light emitting diode (LED) are discussed. Integration of colloidal CdSe quantum dots into a GaN LED active layer is demonstrated. The conductivity of the overgrowth was examined by circular transmission line method (CTLM). Effects on surface roughness due to the active layer incorporation are examined using atomic force microscopy (AFM). LED test devices were fabricated and electroluminescence was demonstrated, the devices exhibit higher turn-on voltages than would be expected for a CdSe active layer.

Download Full-text

High Power 330 nm AlInGaN UV LEDs in the High Injection Regime

MRS Proceedings ◽

10.1557/proc-798-y1.8 ◽

2003 ◽

Vol 798 ◽

Cited By ~ 1

Author(s):

M. Gherasimova ◽

J. Su ◽

G. Cui ◽

J. Han ◽

H. Peng ◽

...

Keyword(s):

Light Emitting Diode ◽

Threading Dislocation ◽

Light Emitting ◽

Force Microscopy ◽

Sapphire Substrates ◽

Atomic Force ◽

Transmission Electron ◽

Dislocation Densities ◽

Dimensional Growth ◽

Uv Leds

ABSTRACTWe report on the growth and testing of the light emitting diode structures incorporating quaternary AlInGaN active region with an emission wavelength of 330 nm. Small area circular devices were fabricated, yielding the output power of 110 μW measured with a bare-chip configuration in a high current injection regime (8 kA/cm2 for a 20 μm diameter device). Structural properties of the constituent epitaxial layers were evaluated by atomic force microscopy and transmission electron microscopy, resulting in the observation of two-dimensional growth morphologies of AlN and AlGaN, and the estimate of threading dislocation densities in the low 109 cm-2 range in the structures grown on sapphire substrates.

Download Full-text

Origins and suppressions of parasitic emissions in ultraviolet light-emitting diode structures

Journal of Materials Research ◽

10.1557/jmr.2010.0135 ◽

2010 ◽

Vol 25 (6) ◽

pp. 1037-1040 ◽

Cited By ~ 4

Author(s):

Weihuang Yang ◽

Shuping Li ◽

Hangyang Chen ◽

Dayi Liu ◽

Junyong Kang

Keyword(s):

Quantum Wells ◽

Uv Light ◽

Light Emitting Diode ◽

Multiple Quantum ◽

Light Emitting ◽

Force Microscopy ◽

Uv Led ◽

Hole Blocking Layer ◽

To Come ◽

P Type

The AlGaN-based ultraviolet (UV) light-emitting diode (LED) structures with AlN as buffer were grown on sapphire substrate by metalorganic vapor-phase epitaxy (MOVPE). A series of cathodoluminescence (CL) spectra were measured from the cross section of the UV-LED structure using point-by-point sampling to investigate the origins of the broad parasitic emissions between 300 and 400 nm, and they were found to come from the n-type AlGaN and AlN layers rather than p-type AlGaN. The parasitic emissions were effectively suppressed by adding an n-type AlN as the hole-blocking layer. Electroluminescence (EL) and atomic force microscopy (AFM) measurements have revealed that the interface abruptness and crystalline quality of the UV-LED structure are essential for the achievement of the EL emissions from the multiple quantum wells (MQWs).

Download Full-text

Local nanotip arrays sculptured by atomic force microscopy to enhance the light-output efficiency of GaN-based light-emitting diode structures

Nanotechnology ◽

10.1088/0957-4484/25/19/195401 ◽

2014 ◽

Vol 25 (19) ◽

pp. 195401 ◽

Cited By ~ 3

Author(s):

Chun-Ying Huang ◽

Yung-Chi Yao ◽

Ya-Ju Lee ◽

Tai-Yuan Lin ◽

Wen-Jang Kao ◽

...

Keyword(s):

Atomic Force Microscopy ◽

Light Emitting Diode ◽

Light Output ◽

Light Emitting ◽

Force Microscopy ◽

Atomic Force ◽

Output Efficiency

Download Full-text

Quaternary AlInGaN MQWs for Ultraviolet LEDs

MRS Proceedings ◽

10.1557/proc-693-i4.4.1 ◽

2001 ◽

Vol 693 ◽

Author(s):

J. P. Zhang ◽

J. W. Yang ◽

V. Adivarahan ◽

H. M. Wang ◽

Q. Fareed ◽

...

Keyword(s):

Quantum Wells ◽

Light Emitting Diode ◽

Atomic Layer ◽

Optical Quality ◽

Multiple Quantum ◽

Light Emitting ◽

Force Microscopy ◽

Peak Emission Wavelength ◽

Pulsed Atomic Layer Epitaxy ◽

20 Nm

AbstractWe report a pulsed atomic layer epitaxy (PALE) growth technique for quaternary AlInGaN films for ultraviolet optoelectronic applications. Using the PALE approach high quality quaternary AlInGaN/AlInGaN multiple quantum wells (MQWs) were successfully grown over sapphire substrates. From X-ray diffraction, atomic force microscopy, and photoluminescence study, a high structural and optical quality was established for the AlInGaN MQWs. Incorporating the PALE grown quaternary MQWs as the active layer of light emitting diode (LED) on sapphire or SiC substrates we also demonstrated room temperature deep ultraviolet electroluminescence under dc and pulsed electrical pumping. The peak emission wavelength can be tuned from 305 nm to 340 nm with spectrum FWHM of about 20 nm by varying the alloy compositions of the quaternary AlInGaN active layers using PALE. Comparative study of LEDs over sapphire and SiC substrates was also done in order to determine the influence of epilayer design on the performance parameters and the role of the substrate absorption.

Download Full-text

Effect of GaN Surface Treatment on the Morphological and Optoelectronic Response of Violet Light Emitting Diodes

MRS Proceedings ◽

10.1557/proc-831-e1.8 ◽

2004 ◽

Vol 831 ◽

Author(s):

Muhammad Jamil ◽

James R. Grandusky ◽

Fatemeh Shahedipour-Sandvik

Keyword(s):

Organic Solvents ◽

Light Emitting Diode ◽

Photoemission Spectroscopy ◽

Light Emitting ◽

X Ray ◽

Force Microscopy ◽

Treatment Processes ◽

Atomic Force ◽

Short Period ◽

High Roughness

ABSTRACTWe report on the study of the effect of various surface chemical treatment processes of n-GaN template layers used for subsequent growth of light emitting diode (LED) structures. The treatment procedure included cleaning in organic solvents, organic solvents followed by 5 minutes of HCl, organic solvents and 5 minutes of HCl followed by 2 minutes and finally 10 minutes of HF treatment. Chemical, optical and electrical properties of the surfaces of GaN and InGaN-based LED structures were systematically investigated by x-ray photoemission spectroscopy (XPS), auger electron spectroscopy (AES), atomic force microscopy (AFM), photoluminescence (PL) and electroluminescence (EL) spectroscopy. GaN layers that were grown on the samples treated with HCl and HF showed dramatically different surfaces having high density of 3D structures with high roughness. As measured by AFM, growth of the LED structure on top of the GaN layer continued the 3D-growth mode. LED structures grown on the HCl and HF treated GaN template layers showed minimal to no PL and EL emission and failed after a short period. We suggest a qualitative model of the growth that could potentially explain the underlying phenomena leading to such pronounced changes in the optoelectronic properties and surface conditions of the LED structures due to the treatment of the initial template layers.

Download Full-text

Enhanced Device Performance of GaInN-Based Green Light-Emitting Diode with Sputtered AlN Buffer Layer

Applied Sciences ◽

10.3390/app9040788 ◽

2019 ◽

Vol 9 (4) ◽

pp. 788 ◽

Cited By ~ 8

Author(s):

Seiji Ishimoto ◽

Dong-Pyo Han ◽

Kengo Yamamoto ◽

Ryoya Mano ◽

Satoshi Kamiyama ◽

...

Keyword(s):

Quantum Wells ◽

Buffer Layer ◽

Light Emitting Diode ◽

Light Output ◽

Green Light ◽

Device Performance ◽

Multiple Quantum ◽

Light Emitting ◽

Current Characteristics ◽

Aln Buffer

In this study, we compared the device performance of GaInN-based green LEDs grown on c-plane sapphire substrates with a conventional low temperature GaN buffer layer to those with a sputtered-AlN buffer layer. The light output power and leakage current characteristics were significantly improved by just replacing the buffer layer with a sputtered-AlN layer. To understand the origin of the improvement in performance, the electrical and optical properties were compared by means of electro-reflectance spectroscopy, I–V curves, electroluminescence spectra, L–I curves, and internal quantum efficiencies. From the analysis of the results, we concluded that the improvement is mainly due to the mitigation of strain and reduction of the piezoelectric field in the multiple quantum wells active region.

Download Full-text

Transferable Substrateless GaN LED Chips Produced by Femtosecond Laser Lift-Off for Flexible Sensor Applications

Proceedings ◽

10.3390/proceedings2130891 ◽

2018 ◽

Vol 2 (13) ◽

pp. 891 ◽

Cited By ~ 1

Author(s):

Nursidik Yulianto ◽

Steffen Bornemann ◽

Lars Daul ◽

Christoph Margenfeld ◽

Irene Manglano Clavero ◽

...

Keyword(s):

Light Emitting Diode ◽

Laser Pulses ◽

Ultrashort Laser Pulses ◽

Light Emitting ◽

Force Microscopy ◽

Sensor Applications ◽

Atomic Force ◽

Lift Off ◽

Pulse Energies ◽

Ultrashort Laser

Transferable substrate-less InGaN/GaN light-emitting diode (LED) chips have successfully been fabricated in a laser lift-off (LLO) process employing high power ultrashort laser pulses with a wavelength of 520 nm. The irradiation of the sample was conducted in two sequential steps involving high and low pulse energies from the backside of the sapphire substrate, which led to self-detachment of the GaN stack layer without any additional tape release procedure. To guarantee their optoelectrical function and surface quality, the lifted LED chips were assessed in scanning electron microscopy (SEM) and electroluminescence (EL) measurements. Moreover, surface characterizations were done using atomic force microscopy (AFM) and Auger Electron Spectroscopy (AES).

Download Full-text