Researchers Demonstrate Record-High Molecular Beam Epitaxy Growth Rates
Georgia Institute of Technology researchers affiliated with the NSF-funded Engineering Research Center (ERC) for Quantum Energy and Sustainable Solar Technologies (QESST), which is headquartered at Arizona State University, demonstrated record-high growth rates for molecular beam epitaxy (MBE). This major accomplishment was recognized in 2015 at the oldest-running U.S. semiconductor conference (WOCSEMMAD), where QESST’s Brendan Gunning received the “most valuable contribution” award (see top figure).
The high growth rate demonstrated by the researchers will enable growth of thick indium gallium nitride (InGaN) layers required for high-efficiency nitride-based solar cells. This improvement in growth technology will have great impact on commercialization of low-cost nitride solar cells.
Although InGaN alloys are promising candidates for full-solar-spectrum photovoltaic applications, these alloys exhibit major challenges, such as growing thick, high-quality InGaN layers. Major maintenance has been performed on the Georgia Tech MBE system, with a new nitrogen plasma source and two additional cryogenic pumps that allow for higher growth rates while still maintaining a high-purity growth environment.
By varying both the RF power and the N2 flow, researchers at Georgia Tech have been able to achieve growth rates ranging from 950 nm/hr to ~8 μm/hr with excellent uniformity over a 2” wafer. Illustrative growth rates are depicted in the accompanying graph.