Passivation of Germanium Surfaces by a Quinhydrone--Methanol Solution Treatment

概要

論文の詳細を見る
The bulk lifetime of minority carriers, $\tau_{\text{b}}$, in germanium (Ge) is one of the most important material parameters in the design and fabrication of Ge-based solar cells. Surface passivation of Ge substrates is indispensable to the accurate evaluation of $\tau_{\text{b}}$. We have found that a newly developed wet chemical treatment, quinhydrone--methanol (Q/M) solution treatment, effectively passivates Ge surfaces, achieving a surface recombination velocity ($S$) of less than 20 cm/s. It has been clarified that oxide layers containing the molecules from the Q/M solution were formed on the Ge surfaces treated with the Q/M solution. Ge dangling bonds (DBs) are thought to be terminated by these oxygen related molecules. Band bending in the Ge substrates induced by the oxide layers adsorbed on the Q/M-treated Ge surface can contribute to the reduction in $S$. We also briefly discuss the properties of a recombination center found in the bulk of highly resistive Ge substrates.
2011-07-25