High reverse voltage amorphous silicon p-i-n diodes

Abstract

New types of a‐Si:H p‐i‐n diodes, capable of sustaining high reverse electric fields up to 6×10⁵ V/cm with very low leakage currents, have been designed specifically for charged particle detection. Because of the low hole mobility and lifetime in this type of material, very high applied fields are required to collect a large fraction of the charge carriers generated by an ionizing particle. Since the leakage current is shown to be essentially due to electron tunneling through the p‐doped layer, the new design includes a thicker p layer (300 nm) at the expense of an increased surface leakage current. An appropriate etching of the top doped layer around the electrode is then required to eliminate such currents. A model, taking into account the doped layer conductivities, is presented to roughly compare the reverse current‐voltage characteristics of the samples before and after etching.