The photovoltages on the free surface of zinc oxide single crystal wafer were measured by directing the incident light from the upper side (free surface side) and the lower side (ZnO-Al contact side). The polarity of upper side photovoltage V_U was positive and that of lower side photovoltage V_L was negative.
It has been found that the observed photovoltages are composed of three different componts, that is, the change of surface barrier height, ΔV_b, the surface drift voltage, V_drif, and the Dember voltager V_D. The first component, ΔV_b, is caused by the decrease of chemisorbed oxygen ions under the illumination of light. Though this component is included in the upper side photovoltag, it is not included in the lower side one because the ΔV_b component at the lower side surface can not be detected by the measurement of the contact potential difference of wafer free surface, and, further, the effect of lower side illumination for the upper side ΔV_b component is negligible due to the attenuation of light intensity through the crystal.
The second component V_drif means the drift separation of electrons and holes generated by the incident light at the surface of crystal. This component included positively in upper side photovoltage, but it will be negative in lower side photovoltage.
The third component is the Dember voltage and this is caused by the difference of mobilities of electron and hole, and the difference of their densities in the carrier generated region. The polarity of V_D is positive in upper side photovoltage and negative iri lower side one.
Upper and lower photovoltages, V_U, and, V_L, of the single crystal of zinc oxide are given by the following equations
V_U=V_D+V_drif+ΔV_b,
V_L=-(V_D+V_drif).

View full abstract

A practical instrumentation to measure high speed photoresponse of a photoconductor blocking cell is discribed.
A general formula which expresses the photoresponse was derived taking light pulse width Δt, penetration depth Δx, sample thickness L and lifetimes and mobilites of electrons and holes τ_e, τ_h, μ_e, μ_h into consideration. In extreme cases the formura coincided with those previously reported by othor authors.
An auramine hydrochloride single crystal was measured as an example and lifetimes and mobility of carriers were estimated.

View full abstract

This paper describes magnetic brush developing device of sleeve type apt to high speed copier.
It is studies under a variety of conditions of magnet arrangement, magnetic flux density of developed magnet pole and electrophotographic print quality.
To obtain good quality of electrophotographic print, the relation between magnet arrangement and magnetic flux density of developed magnet pole is very important.

View full abstract

This paper describes to applied for bias voltage and print quality for magnetic developing brush.
Residual potential of photoconductor is almost present with a fog and compensates by bias potential acting on developing brush.
A fog can not observed by the bias potential applying on more than 300 volt.
Net bias potential s a nearly half on applied bias potential.

View full abstract