XOI holds promise of replacing silicon
1 min read
Researchers at the US Department of Energy's Lawrence Berkeley National Laboratory (Berkeley) and the University of California Berkeley have successfully integrated ultrathin layers of InAs onto a silicon substrate to create a nanoscale transistor with what are said to be 'excellent electronic properties'.
"We've shown a simple route for the heterogeneous integration of indium arsenide layers down to a thickness of 10nm on silicon substrates," says Ali Javey, pictured right, a faculty scientist in Berkeley's Materials Sciences Division who led this research.
"The devices we subsequently fabricated were shown to operate near the projected performance limits of III-V devices with minimal leakage current. Our devices also exhibited superior performance in terms of current density and transconductance as compared to silicon transistors of similar dimensions."
The development is an important step in the search for materials to replace silicon in future devices. However, the challenge has been to develop a technology that is compatible with cmos manufacturing. Indium arsenide offers several advantages as a replacement for silicon including superior electron mobility and velocity.
Berkeley is calling its approach XOI, or compound semiconductor on insulator. This draws upon today's silicon on insulator, or SoI, technology. Javey said: "Using an epitaxial transfer method, we transferred ultrathin layers of single crystal InAs on silicon/silica substrates, then fabricated devices using conventional processing techniques in order to characterise the XOI material and device properties."
Javey said the performance of the XOI transistors were due to the small dimensions of the active X layer and the role played by quantum confinement. Although the work was based only on InAs, the technology is believed to be suitable for other compound III/V semiconductors.
"We believe … our technique should make it possible to fabricate p- and n- type transistors on the same chip for complementary electronics based on optimal III–V semiconductors," Javey concluded.
