Streetman details continuing impact of the semiconductor

Today, semiconductors in all their various forms are integral to American life.

Ben Streetman, professor in the electrical and computer engineering department at the University of Texas at Austin, detailed the exponential evolution of semiconductors and their applications as part of the continuing 50th anniversary lecture series for the College of Engineering at the University of Texas at Arlington.

“Sometimes it’s easy to forget what things were like before. For example, the integrated circuit,” Streetman said.

When transistors were created in 1947, few people could see their long-term technological applications. The transistor, a semiconductor used to amplify or switch electronic signals, evolved into the integrated circuit in the late 1950s, but most electronics still used vacuum tubes, which were cheap.

Semiconductors are found in electronics of all sorts, from portable USB drives to iPods to cell phones, digital cameras to radios. The original transistor was developed by John Bardeen and Walter Brattain, who earned a Nobel Prize in physics along with their boss at Bell Labs, William Shockley.

The integrated circuit brought a shift to silicon, which is still widely used and is an incredibly versatile material, Streetman said. Photolithography, or using light to shine through a mask onto a silicon wafer to build a circuit, became practice and engineers and researchers could suddenly put huge computational memory on one small device.

“When these inventions were made, I’m not sure they knew what the impact would be at the time,” Streetman said.

As techniques became more sophisticated, larger silicon wafers could be used and even more transistors could be built onto each one. Moore’s law is probably familiar to many people and dictates that there is an exponential increase of transistor count and decrease of sizes of transistors with time. In other words: capacity doubles every year. From the 1970s, skeptics have been waiting for engineers to reach the end of the limits, Streetman said.

“Everybody predicted that this would taper off . . . and amazingly, creative engineers find a way to make it happen,” he said.

Today, semiconductors are the foundation for flash memory, like that found in a portable USB drive, and in optoelectronic devices, which detect, manipulate and generate light, like solar cells, lasers and light-emitting diodes (LEDs).

Researchers still are searching for ways to make solar cells more efficient, because large surface areas currently are necessary to generate significant amounts of money and the cells are still expensive. LEDs are more energy-efficient and long-lasting than incandescent lightbulbs, and Streetman said he expects to see more widespread applications of the lights.

“For those of you who want to save the world from carbon, this will probably play a role,” he said.

For anyone who’s wondering whether LEDs are being used more today, Streetman pointed to the massive high-definition video screens at the Dallas Cowboys Stadium, which together use more than 10 million LEDs.

Semiconductor lasers, also created in the early ‘60s, have commercial applications in electronics like CD players and laser printers.

Streetman did say engineers and researchers will probably run into some kind of unknown barrier to advancing semiconductors so quickly at some point in the future.

“The notion that Moore’s law is going to disappear is probably correct,” he said. “It’s just hard to know when that’s going to happen.”

However, semiconductors are now a necessary part of modern life. When asked whether it’s been consumer demand that’s driven research and if the general public would finally be satisfied with its electronics in the future, he said the research has actually driven consumer demand.

“The consumer demand has followed the technology change,” he said. “People really didn’t know they needed flash memory until it came along. ... I think the technology has caused the change as much as the response to it.”

And for every change, for every semiconductor in a faster computer or a cell phone that can hold more applications, there are hundreds and thousands of engineers working away at advancement, he said. While some researchers, like Brattain and Bardeen, are recognized for their contributions, he said, there are countless others who make small contributions that add up to change the technology we all use.