News Article

Voids Boost LED Light Emission

Higher light extraction efficiency results from a novel architecture formed by laser drilling and photochemical etching
A partnership between researchers in the US and China has increased LED output power by more than one-fifth via the creation of air gaps within the device.To deliver the increase in extraction efficiency, the researchers from National Chung Hsing University and Yale University drilled holes with a laser, before etching a heavily doped GaN layer beneath the LED structure.

Fabrication of these novel LEDs began with growth of an epistructure on sapphire that had a low-temperature buffer, an 1.2µm-thick undoped GaN layer, a heavily doped 0.2µm -thick GaN layer and a 0.2µm-thick undoped GaN layer. On top of this they deposited a relatively conventional device structure, which was capped with a 250 nm-thick layer of the transparent conductive material indium tin oxide.

Engineers employed a 355 nm laser to drill 10µm -diameter holes down to the heavily doped n-type layer, and used an electrochemical wet-etching process to create disk-shaped voids with a diameter of 40µm.

Driven at 20 mA, the etched LED delivered a light output power that was 22 percent higher than that of the control. However, this gain in the output came at the expense of a small increase in operating voltage from 3.12 V to 3.19 V, due to the slightly reduced emission area and the increased resistance of the treated LED structure.

Ref. C. -F. Lin et. al. Appl. Phys. Express 7 076501 (2014)

AngelTech Live III: Join us on 12 April 2021!

AngelTech Live III will be broadcast on 12 April 2021, 10am BST, rebroadcast on 14 April (10am CTT) and 16 April (10am PST) and will feature online versions of the market-leading physical events: CS International and PIC International PLUS a brand new Silicon Semiconductor International Track!

Thanks to the great diversity of the semiconductor industry, we are always chasing new markets and developing a range of exciting technologies.

2021 is no different. Over the last few months interest in deep-UV LEDs has rocketed, due to its capability to disinfect and sanitise areas and combat Covid-19. We shall consider a roadmap for this device, along with technologies for boosting its output.

We shall also look at microLEDs, a display with many wonderful attributes, identifying processes for handling the mass transfer of tiny emitters that hold the key to commercialisation of this technology.

We shall also discuss electrification of transportation, underpinned by wide bandgap power electronics and supported by blue lasers that are ideal for processing copper.

Additional areas we will cover include the development of GaN ICs, to improve the reach of power electronics; the great strides that have been made with gallium oxide; and a look at new materials, such as cubic GaN and AlScN.

Having attracted 1500 delegates over the last 2 online summits, the 3rd event promises to be even bigger and better – with 3 interactive sessions over 1 day and will once again prove to be a key event across the semiconductor and photonic integrated circuits calendar.

So make sure you sign up today and discover the latest cutting edge developments across the compound semiconductor and integrated photonics value chain.



Search the news archive

To close this popup you can press escape or click the close icon.
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:
Live Event