Band alignment at amorphous/crystalline silicon hetero-interfaces

We present an investigation of the band offsets in amorphous/crystalline silicon heterojunctions (a-Si:H/c-Si) using low energy photoelectron spectroscopy, ellipsometry and surface photovoltage data. For a variation of deposition conditions that lead to changes in hydrogen content and the thereby the a-Si:H band gap by ∼180 meV, we find that mainly the conduction band offset ΔEV varies, while ΔEC stays constant within experimental error. This result can be understood in the framework of charge neutrality (CNL) band lineup theory.