Loading...
News Article

Process Paves Way for More Efficient Lasers, LEDs

News

North Carolina State University team develops MOCVD process that produces the highest concentration of holes in p-type III-Nitride material

Researchers from North Carolina State University have developed a new process that makes use of existing industry standard techniques for making III-nitride semiconductor materials, but results in layered materials that will make LEDs and lasers more efficient.

A challenge for people who make LEDs and lasers has been that there was a limit on the number of holes that you can make in p-type III-nitride semiconductor materials that are created using MOCVD. But that limit just went up.

“We have developed a process that produces the highest concentration of holes in p-type material in any III-Nitride semiconductor made using MOCVD,” says Salah Bedair, co-author of a paper on the work and a distinguished professor of electrical and computer engineering at NC State. “And this is high quality material – very few defects – making it suitable for use in a variety of devices.”

In practical terms, this means more of the energy input in LEDs is converted into light. For lasers, it means that less of the energy input will be wasted as heat by reducing the metal contact resistance.

LEDs contain three main layers: an n-type layer where electrons originate; the “active region,” which consists of multiple quantum wells of InGaN and GaN and a p-type layer, where the holes originate.

The researchers use a growth technique called “semibulk growth” to produce InGaN templates. The template is made of dozens of layers of InGaN and GaN. The researchers use these templates for the n-type region to reduce complications that arise with the growth of the quantum wells. The insertion of the GaN layer in between the InGaN layers in semibulk reduces defects due to the lattice mismatch between the semibulk template and the GaN substrate, as well as filling the pits that form on the surface.

In their new work, the researchers demonstrated that the semibulk growth approach can be used for the p-type layer in LEDs to increase the number of holes. This new approach is cost effective from a manufacturing standpoint, since III-nitride based LED devices can be done in one growth via MOCVD, without a lengthy processing time in between.

Using this technique, the researchers were able to achieve a hole density of 5 × 1019 cm-3 in the p-type material. Previously, the highest hole concentration achieved in p-type III-nitride materials using MOCVD was about an order of magnitude lower.

The researchers also applied these InGaN templates as substrates for LED structures to address the long-lasting problem called the “green gap,” where the LED output deteriorates when emitting in the green and yellow part of the spectrum.

One of the main reasons for the green gap is the large lattice mismatch between the light emitting part of the material, the quantum well, when gallium nitride substrates are used. The researchers have demonstrated that replacing the GaN substrates with InGaN templates results in improved LED performances.

The researchers compared the LED emission spectrum for the same quantum well emitting in blue when grown on GaN substrate and emitting either in green or yellow when grown on different indium gallium nitride templates. A 100 nm shift in the emission wavelength was achieved due to the application of the InGaN templates.

The graphs above show electroluminescence measurements of (a) Blue LED on GaN, (b) Green LED on InGaN template, (c) Near yellow LED on InGaN template. The insets of Fig. 1(b) and Fig. 1(c) show the image of the emission at 1.5 mA injection current.

'P-type InxGa1-xN semibulk templates (0.02 < x < 0.16) with room temperature hole concentration of mid-1019 cm-3 and device quality surface morphology” is published in the journal Applied Physics Letters.

'Shifting LED emission from blue to the green gap spectral range using In0.12Ga0.88N relaxed templates' is published in Superlattices and Microstructures

SPONSOR MESSAGE

Secure Your Hydrogen Supply

A study supply of high-purity hydrogen is critical to semiconductor fabrication. Supply chain interruptions are challenging manufacturers, leading to production slowdowns and stoppages. On-site hydrogen generation offers a scalable alternative for new and existing fabs, freeing the operator from dependence on delivered gas.

Plant managers understand the critical role that hydrogen plays in semiconductor fabrication. That important job includes crystal growth, carrier gas, wafer annealing, and in the emerging Extreme UV Lithography (EUV) that will enable new generations of devices. As the vast need for semiconductors grows across all sectors of world economies, so does the need for high-purity hydrogen.

Take control with Nel on-site hydrogen generation.

Read more
SiC MOSFETs: Understanding the benefits of plasma nitridation
Wolfspeed reports Q2 results
VueReal secures $40.5m to scale MicroSolid printing
Mitsubishi joins Horizon Europe's FLAGCHIP project
Vishay launches new high voltage SiC diodes
UK team leads diamond-FET breakthrough
GaN adoption at tipping point, says Infineon
BluGlass files tuneable GaN laser patents
QD company Quantum Science expands into new facility
Innoscience files lawsuit against Infineon
Riber revenues up 5% to €41.2m
Forvia Hella to use CoolSiC for next generation charging
Photon Design to exhibit QD simulation tool
Ortel transfers CW laser fabrication to Canada
Luminus adds red and blue multi-mode Lasers
PseudolithIC raises $6M for heterogeneous chiplet tech
Mesa sidewall design improves HV DUV LEDs
IQE revenue to exceed expectations
'Game-changing' VCSEL system targets clinical imaging
German start-up secures finance for SiC processing tech
Macom signs preliminaries for CHIPS Act funding
IQE and Quintessent partner on QD lasers for AI
EU funds perovskite tandems for fuel-free space propulsion
EU to invest €3m in GeSi quantum project
Transforming the current density of AlN Schottky barrier diodes
Turbocharging the GaN MOSFET with a HfO₂ gate
Wolfspeed launches Gen 4 SiC MOSFET technology
Report predicts high growth for UK's North East
Element Six unveils Cu-diamond composite
SemiQ launches hi-rel 1700V SiC MOSFETs
Lynred to exhibit Eyesential SWIR sensor for machine vision
Thorlabs buys VCSEL firm Praevium Research
×
Search the news archive

To close this popup you can press escape or click the close icon.
Logo
x
Logo
×
Register - Step 1

You may choose to subscribe to the Compound Semiconductor Magazine, the Compound Semiconductor Newsletter, or both. You may also request additional information if required, before submitting your application.


Please subscribe me to:

 

You chose the industry type of "Other"

Please enter the industry that you work in:
Please enter the industry that you work in:
 
x
Adblocker Detected
Please consider unblocking adverts on this website