In Breakthrough Method of Creating Solar Cell Material, NREL Scientists Prove the Impossible Really Isn’t
https://www.nrel.gov/news/program/2019/breakthrough-method-creating-solar-cell-scientists-prove-impossible-is-not.html
Scientists at the National Renewable Energy Laboratory (NREL) achieved a technological breakthrough for solar cells previously thought impossible.
The scientists successfully integrated an aluminum source into their hydride vapor phase epitaxy (HVPE) reactor, then demonstrated the growth of the semiconductors aluminum indium phosphide (AlInP) and aluminum gallium indium phosphide (AlGaInP) for the first time by this technique.
“There’s a decent body of literature that suggests that people would never be able to grow these compounds with hydride vapor phase epitaxy,” said Kevin Schulte, a scientist in NREL’s Materials Applications & Performance Center and lead author of a new paper highlighting the research. “That’s one of the reasons a lot of the III-V industry has gone with metalorganic vapor phase epitaxy (MOVPE), which is the dominant III-V growth technique. This innovation changes things.”
The article, “Growth of AlGaAs, AlInP, and AlGaInP by Hydride Vapor Phase Epitaxy,” appears in the journal ACS Applied Energy Materials.
III-V solar cells—so named because of the position the materials fall on the periodic table—are commonly used in space applications. Notable for high efficiency, these types of cells are too expensive for terrestrial use, but researchers are developing techniques to reduce those costs.
One method pioneered at NREL relies on a new growth technique called dynamic hydride vapor phase epitaxy, or D-HVPE. Traditional HVPE, which for decades was considered the best technique for production of light-emitting diodes and photodetectors for the telecommunications industry, fell out of favor in the 1980s with the emergence of MOVPE. Both processes involve depositing chemical vapors onto a substrate, but the advantage belonged to MOVPE because of its ability to form abrupt heterointerfaces between two different semiconductor materials, a place where HVPE traditionally struggled.
That’s changed with the advent of D-HVPE.
Growth of AlGaAs, AlInP, and AlGaInP by Hydride Vapor Phase Epitaxy
https://pubs.acs.org/doi/full/10.1021/acsaem.9b02080