Influence of reactive gas pressure on the deposition of an AlN protective film for organic photoconductor

The deposition of a protective AlN film for hardening and smoothing of organic photoconductor (OPC) surface is an effective method to prolong the operating lifetime of the OPC. In this work, the electrophotographic properties, surface microhardness and surface roughness of AlN coated OPC as a function of N₂ gas pressure during the sputtering of AlN film were systematically studied and optimized. When the N₂ partial pressure increases, the surface roughness increases and the surface hardness decreases. When the N₂ pressure is around 2.7 × 10^-1 Pa (2 mTorr), the electrophotographic properties reach optimized conditions. When the pressure is increased to 5.3 × 10^-1 Pa (4 mTorr), the surface roughness increases quickly, the surface hardness decreases, and the electrophotographic properties can deteriorate quickly as a result of the target poisoning phenomenon during the sputtering process. From this work, it is clearly shown that the deposition of AlN protective film can effectively increase the surface hardness of an OPC without causing a deterioration on the electrophotographic properties of the OPC, thereby prolonging the operating lifetime of the OPC. In fact, AIN coated OPC is expected to have a better electrophotographic performance in terms of image development.