Niobium Oxide on Silicon

Pellerin, Emma

Student Work

Niobium Oxide on Silicon

Public Deposited

We studied the surface chemistry, energy band bending, and lifetime retain- ment of HF-etched intrinsic silicon wafers that received atomically deposited ultra-thin layers of Nb2O5 and surface derivatized (3,3,3–trifluoropropyl)tri- methoxysilane. Nb2O5 has two main advantages; it passivates with fewer layers than other metal oxides and it’s fermi energy levels are harmonious with those displaced by the development of native SiOx on the surface. The (3,3,3-trifluorpropyl)trimethoxysilane was chosen to aid in the optimization of surface organic contacts for future tandem junction solar cell systems as attempted before by our group. The synthesis and forming gas annealing procedures for the Nb2O5 layers were outsourced and transferred from the Strandwitz group at Lehigh University, along with the sample’s initial SRV measurements. Once received, samples were scanned by XPS to verify the quality of metal oxide on the surface and other applicable chemical species, samples were also scanned following silane derivatization to prove surface contacts created. TRMPS was utilized continuously to model changes in SRV and to understand what experiments contribute to those changes. While Nb2O5 layers demonstrated increased lifetime retainment, lifetimes decrease by 200–300 μs following silanization. This trend is measured over several months and is an overall increase compared to plain i-Si with native-grown SiOx over the same time period, but elucidates the need for further investi- gation into silicon’s surface environment.

This report represents the work of one or more WPI undergraduate students submitted to the faculty as evidence of completion of a degree requirement. WPI routinely publishes these reports on its website without editorial or peer review.

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