Chip manufacturers beware: There's a newfound flaw in our understanding of transistor noise, a phenomenon affecting the on-off switch that makes computer circuits possible.

That flaw soon will stand in the way of creating more efficient, lower-powered devices like cell phones and pacemakers unless we solve it, claim engineers at the National Institute of Standards and Technology (NIST) who discovered the problem,.

While exploring transistor behavior, the research team found evidence that a widely accepted model explaining errors caused by electronic "noise" in the switches doesn't fit the facts. A transistor must be made from highly purified materials to function. Defects in those materials, like rocks in a stream, can divert the flow of electricity and cause the device to malfunction. That, in turn, makes the transistor appear to fluctuate erratically between "on" and "off" states.

For decades, the industry largely has accepted a theoretical model that identifies such defects and helps guide designers' efforts to mitigate them. Those days are ending, asserts NIST's Jason Campbell, who has studied the fluctuations between on-off states in progressively smaller transistors. The theory, known as the elastic tunneling model, predicts that as transistors shrink, the fluctuations should correspondingly increase in frequency.

Campbell's group, however, has shown that even in nanometer-sized transistors, the fluctuation frequency remains the same.

"This implies that the theory explaining the effect must be wrong," Campbell says. "The model was a good working theory when transistors were large, but our observations clearly indicate that it's incorrect at the smaller nanoscale regimes where industry is headed."

The findings have implications for the low-power transistors in demand in high-tech consumer technology, such as laptop computers. Low-power transistors are coveted because using them on chips allows devices to run longer on less power. But Campbell says that the fluctuations his group observed grow even more pronounced as the power decreased.