A research team at National Taiwan University has achieved a breakthrough in semiconductor characterisation — good news for Taiwan's chip industry and its competitiveness in advanced manufacturing processes.

• The team led by Chiu Ya-ping of NTU's Department of Physics has developed a new characterisation technique that, for the first time, directly measures the "carrier transfer length" in two-dimensional semiconductor transistors. The results were published in the world-leading journal Nature.
• This length is the effective distance electrons must travel when passing from the metal into the semiconductor. As chips are made ever smaller, this contact region must shrink accordingly, and it directly affects whether a device can function properly.
• In the past it could only be inferred indirectly using models, and the estimates from different studies differed by more than tenfold — in effect, there was no reliable standard.
• The team cleaved the device in a vacuum to expose a clean cross-section while keeping it under current, and measured it directly with a probe, obtaining a value of about 2 nanometres — far smaller than the 9.25 nanometres inferred by older methods.
• This demonstrates that single-layer molybdenum disulphide with bismuth (Bi) contacts has the potential to support the next generation of chips, and the technique is applicable to a variety of materials.

Outlook: This direct characterisation tool is expected to become a new standard for interface engineering in advanced semiconductors, helping chips to continue shrinking.