Non-Onsager mechanism of long-wave photogeneration in amorphous selenium at high electric fields

Abstract

The quantum efficiency of the free-carrier-photogeneration in amorphous selenium avalanche blocking structures is studied experimentally in a wide range of wavelengths (380–600 nm) at high electric fields (10−112.5Vμm−1). While at comparatively small excitation wavelengths (up to ≃540nm), our experimental results are consistent with the Onsager theory of electron-hole pair dissociation [L. Onsager, Phys. Rev. 54, 554 (1938)], at larger wavelengths (540–600 nm) and high electric fields Onsager theory fails to explain our results. The reason for the failure of the Onsager approach is discussed and an alternative theoretical tool is adopted to account for the experimental observations.