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The effect of electron traps on the residual voltage in chalcogenide photoreceptors is discussed. In order to cancel hole traps in these photoreceptors and to decrease the residual voltage, it is useful to introduce electron traps. It is seen from numerical calculation that, in the case of uniform distribution of the normalized electron trap density N tn, the introduction of N tn=1.0 decreases the the residual voltage to one tenth of N tn=0. On the other hand, in the case of exponential distribution of the normalized electron trap N tn(x)=N 0exp (-A x), it is interesting that the residual voltage V r is greatly influenced by the electron trap density at the interface of the substrate.

A numerical analysis of the residual voltage on an electrophotographic plate is presented for a photodischarge process characterized by carrier trapping and release parameters. The physical model is described by a set of one-dimensional transport equations with appropriate initial and boundary conditions. Examples of calculations are given for two models involving one and two hole trap levels. It is shown that a residual voltage can be derived which is valid for the decay process in amorphous Se film under typical electrophotographic conditions. For one trapping level, a trapping parameter of wr>10-5 are needed to decrease the residual voltage V r. With two trapping levels, the residual voltage is mainly influenced by the deep trap E t1.

We propose a method useful for studying the energy distribution of deep gap states in amorphous semiconductors. The method is a sensitive and direct technique based upon the analysis of time dependence of residual voltage in photoreceptors under isothermal conditions. This enables us to map out the energy distribution of deep gap states in amorphous semiconductors. Experimental results using the method for amorphous selenium photoreceptors are demonstrated. Our results are in good agreement with those in the literature.

The residual voltage which appears in a pre-stressed polyethylene film is found to increase with increasing draw ratio and then to decrease again at higher draw ratio. On the other hand, the ratio of a surface potential decay decreases with increasing draw ratio and then again increases at higher ratio. These results are discussed in terms of the change of the carrier transport process, localized state density and carrier mobility.