News Article

First Steps To High Temperature GaN Memory?


Arizona team's epitaxially regrown GaN-on-GaN vertical p-n diodes show promise for next generation space electronics

Scientists at Arizona State University have reported creating a GaN-based memory device that can operate at very high temperatures. The results were published in IEEE Electronic Device Letters (March 2019).

The research is funded by NASA's Hot Operating Temperature Technology (HOTTech) program to support future missions to Mercury and Venus. Temperatures on the surface of Mercury can reach 430degC while those on Venus can climb to 462degC.

The team observed threshold switching and memory behaviours in epitaxially regrown GaN-on-GaN vertical p-n diodes. The mechanism seems to be linked with the conductive path formed by traps in the insulating layer at the regrowth interface after soft breakdown. They say that the device can reliably switch more than 1000 cycles at both room temperature and 300degC with a small fluctuation on the set and reset voltage.

The set voltage increased with the increasing temperature due to the enhanced thermal de-trapping effect that made it harder to form conductive path at high temperatures. The device showed memory behaviours when the reset voltage was higher than 4.4 V. They think this is the first stage towards developing GaN-based memory devices.

In an article in IEEE Spectrum magazine, Yuji Zhao, a scientist at Arizona State University who worked on the project, explained that the device's performance was down to the etching and regrowth processes used during fabrication. After several layers of GaN were deposited, some areas were etched away with plasma, then regrown. That created an interface layer with vacancy sites that are missing nitrogen atoms, said Zhao. “The interface layer is critical for the memory effect,” he says. The researchers believe that the nitrogen vacancies are responsible for capturing and releasing electrons, giving rise to high- and low-resistance states - or 0 and 1 states - in the device.

Above 350 degC, the device lost its memory effect. But its performance returned after the device was brought back to room temperature, says Zhao. “This device is actually very robust,” he says.

Zhao and his team are now testing another version of the device for stability up to 500degC, and for long-term stability.

'Threshold Switching and Memory Behaviors of Epitaxially Regrown GaN-on-GaN Vertical p-n Diodes With High Temperature Stability' by Kai Fu et al; IEEE Electronic Device Letters (March 2019)

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