Info
Info
News Article

Annealing Accelerates Electron Mobility

In-situ annealing nearly doubles electron mobility in InGaAs MISFETs
�A team of researchers from Japan has almost doubled electron mobility in InGaAs MISFETs by performing an annealing step prior to the deposition of a HfO2 gate dielectric.

These efforts by engineers from the National Institute of Advanced Industrial Science and Technology and Sumitomo Chemical will help to enhance the credentials of III-V channels as alternatives to silicon for maintaining the march of Moore's Law. Higher mobilities allow a reduction in operating voltage of the transistor while maintaining its current, thus enabling ICs to maintain performance while consuming less power.

Traditionally, researchers have paired InGaAs MISFETs with an Al2O3 dielectric to create transistors with high mobility and a low interface state density. But the dielectric constant of this oxide is just 9, which is half that of HfO2, the gate dielectric used within the silicon industry today.

A higher dielectric constant is preferred, because it should make it easier to shrink transistor dimensions while maintaining performance. However, replacing Al2O3 with HfO2 has been hampered by a reduction in inversion electron mobility.

The team from Japan has overcome this by loading the epiwafers in an atomic layer deposition tool, and prior to deposition of the dielectric, annealing them in an argon atmosphere for 30 minutes at 300 degC. After this, a film of HfO2 is deposited using a 50-cycle process, before gates are patterned using a standard reactive-ion etching process and metal contacts are added.

X-ray photoelectron spectroscopy measurements on this device, and also on a control that had not been annealed, revealed that the former structure produced a stronger signal at an energy associated with gallium oxides. This occurred because annealing is estimated to increase the thickness of the GaOx from 0.15 nm to 0.20nm.

A series of different electrical measurements by the team showed that the annealed device had a much smaller frequency dispersion around the threshold voltage, which was the result of a decrease in the density of border traps in the HfO2 dielectric.

Mobility in the annealed sample peaked at about 1250 cm2 V-1 s-1 for a surface carrier density of around 2.5 x 1012 cm-2. In comparison, the mobility for the control was just shy of 700 cm2 V-1 s-1 for a surface carrier density of around 3.5 x 1012 cm-2.

The team attributes superior mobility to effective GaOx passivation at the interface between InGaAs and HfO2

�Reference: M. Oda et al. Appl. Phys. Express 7 061202 (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.

REGISTER FOR FREE

VIEW SESSIONS

Info
×
Search the news archive

To close this popup you can press escape or click the close icon.
×
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
Info
X
Info
{taasPodcastNotification}
Live Event