Tiny defects in semiconductors created 'speed bumps' for electrons—researchers cleared the path

phys.org | 6/11/2018 | Staff
donuzumaki (Posted by) Level 3
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UCLA scientists and engineers have developed a new process for assembling semiconductor devices. The advance could lead to much more energy-efficient transistors for electronics and computer chips, diodes for solar cells and light-emitting diodes, and other semiconductor-based devices.

A paper about the research was published in Nature. The study was led by Xiangfeng Duan, professor of chemistry and biochemistry in the UCLA College, and Yu Huang, professor of materials science and engineering at the UCLA Samueli School of Engineering. The lead author is Yuan Liu, a UCLA postdoctoral fellow.

Method - Semiconductor - Layer - Metal - Electrode

Their method joins a semiconductor layer and a metal electrode layer without the atomic-level defects that typically occur when other processes are used to build semiconductor-based devices. Even though those defects are minuscule, they can trap electrons traveling between the semiconductor and the adjacent metal electrodes, which makes the devices less efficient than they could be. The electrodes in semiconductor-based devices are what enable electrons to travel to and from the semiconductor; the electrons can carry computing information or energy to power a device.

Generally, metal electrodes in semiconductor devices are built using a process called physical vapor deposition. In this process, metallic materials are vaporized into atoms or atomic clusters that then condense onto the semiconductor, which can be silicon or another similar material. The metal atoms stick to the semiconductor through strong chemical bonds, eventually forming a thin film of electrodes atop the semiconductor.

Issue - Process - Metal - Atoms - Sizes

One issue with that process is that the metal atoms are usually different sizes or shapes from the atoms in the semiconductor materials that they're bonding to. As a result, the layers cannot form perfect one-to-one atomic connections, which is why small gaps or defects occur.

"It is like trying to fit one layer of Lego brand blocks onto those of a competitor brand," Huang said. "You can force the...
(Excerpt) Read more at: phys.org
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