A team of chemists at the University of Michigan have developed a new method to create single-crystalline semiconductor films, a component of nearly all electronic devices. The team, led by Stephen Maldonado, associate professor of chemistry, invented a more environmentally-friendly and cheaper method to create semiconductor films.
Semiconductors are used to create lasers and LEDs due to the light they emit when they contain impurities, according to the website of the University of Maryland’s School of Engineering. They are also used to fabricate solar cells because of their ability to absorb light and generate a current.
The process discovered by the University of Michigan chemists doesn’t use excess heat and doesn’t require the use of hazardous gas. Instead, the team uses water at room temperature and easy-to-make equipment to create the crystalline semiconductor films.
In an email to the Daily, Maldonado detailed what inspired him and his group to develop this new method for creating semiconductors — emphasizing their interest in discovering “greener ways to do useful chemistry.”
“But another pertinent motivation for this particular work is a desire to build upon a simple finding we came across several years ago,” Maldonado wrote. “We discovered serendipitously liquid metals are useful solvents for semiconductor crystal growth even at room temperature. Accordingly, we have been really motivated to push this concept as far as possible, both for large materials (this work) and nanomaterials (other works of ours).”
The method is more environmentally friendly due to the lack of heat and hazardous gases.
“If you don't have to input energy to generate high temperatures, low vacuums, or reactive precursor molecules (gases), the energy cost and potential environmental impact of the process are necessarily lowered,” Maldonado wrote.
Rackham student Daniel Bier, a student in the Erb institute, wrote in an email to the Daily he would want to reserve judgement on how much greener the newly developed method is, considering the number of factors that can affect the environmental impact of this technology.
“It's easy to say that something is green, but to evaluate how much 'greener' this technology is, you should consider how this new approach will impact energy and material consumption across the supply chain,” he wrote. “This includes the environmental impact of purchasing new capital equipment to build the chips and the amount of energy and raw materials involved in manufacturing.”
Bier also said the change in impact could be very small and by making electronics cheaper, more could be thrown away.
“The biggest question for me is how 'material' is this new technology from an environmental perspective: is the change in energy or material use significant, or just a few percentage points?” he wrote. “Would this make producing electronics so much cheaper that overall manufacturing volumes skyrocket, leading to devices becoming more disposable and ending up in landfills?”
How this discovery will change how semiconductors are created in the future and on a large scale is largely unknown, but has the potential to create waves in the electronics industry, Maldonado said.
“What we developed in our lab is properly best thought of as a prototype,” Maldonado wrote. “We are (predominantly) not engineers in my group, so we have not been focused on the challenges of scale or designing a fabrication assembly line.”
The finding is incredibly important in respect to how different it is from the traditional way to produce semiconductor films, Maldonado said. While the method needs more work, it has shown what is possible.
“I think they (the findings) are important because they demonstrate a radically different way to make useful materials,” Maldonado said. “Basically, we use electrical energy to drive crystallization rather than thermal energy. This work shows that with this concept you can take a raw oxidized source and directly convert it into a highly crystalline semiconductor. By playing with aspects of the system, we have shown that we can control exactly where and how crystallization occurs.”
Maldonado is optimistic about the progress his team has made so far.
“We're not there yet, but we're a lot closer than I thought we would ever be before we started this work.”