Long-range random potential in thin-film structures

Abstract

We develop a theory of long-range random potential caused by charge-density fluctuations in thin nonmetal structures sandwiched between two conducting electrodes. This model applies to many practical systems including thin-film photovoltaics and classical $p\text{\ensuremath{-}}n$ and Schottky junctions. The lateral screening due to the conducting electrodes leads to the screening length close to the structure thickness. We have analytically calculated the random potential amplitude for three practically important cases: point-charged defects, spherical grains, and columnar grains. Implications of our findings for polycrystalline devices are discussed.