Time‐of‐Flight Transient Photoconductivity Technique

Kasap, S. O.

doi:10.1002/9781119579182.ch5

Cited by 4 publications

(2 citation statements)

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“…Since the photocurrent i ph ( t ) is, at any instant, proportional the drift mobility μ e at the location of the drifting carrier package, and since μ e drops exponentially with the As content, it is apparent that the shape of i ph ( t ) cannot simply be ascribed to deep trapping. IFTOF measurements are more accurate, since the carrier packet’s drift is halted for a certain time period, the interruption time t i , and the fractional change in the photocurrent is measured as a function of t i as described in [ 17 ]. An examination of the electron range data in Figure 5 reveals that r e initially increases with C , peaks around ~0.7%, and then drops sharply with the As content.…”

Section: Formulation Of the Modelmentioning

confidence: 99%

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The Effect of Fractionation during the Vacuum Deposition of Stabilized Amorphous Selenium Alloy Photoconductors on the Overall Charge Collection Efficiency

Kasap

2022

Sensors

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The general fabrication process for stabilized amorphous selenium (a-Se) detectors is vacuum deposition. The evaporant alloy is typically selenium alloyed with 0.3–0.5% As to stabilize it against crystallization. During the evaporation, fractionation leads to the formation of a deposited film that is rich in As near the surface and rich in Se near the substrate. The As content is invariably not uniform across the film thickness. This paper examines the effect of non-uniform As content on the charge collection efficiency (CE). The model for the actual CE calculation is based on the generalized CE equation under small signals; it involves the integration of the reciprocal range-field product (the schubweg) and the photogeneration profile. The data for the model input were extracted from the literature on the dependence of charge carrier drift mobilities and lifetimes on the As content in a-Se1−xAsx alloys to generate the spatial variation of hole and electron ranges across the photoconductor film. This range variation is then used to calculate the actual CE in the integral equation as a function of the applied field. The carrier ranges corresponding to the average composition in the film are also used in the standard CE equation under uniform ranges to examine whether one can simply use the average As content to calculate the CE. The standard equation is also used with ranges from the spatial average and average inverse. Errors are then compared and quantified from the use of various averages. The particular choice for averaging depends on the polarity of the radiation-receiving electrode and the spatial variation of the carrier ranges.

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Section: Formulation Of the Modelmentioning

confidence: 99%

“…The latter is integrated to obtain the signal Q c , the collected charge. The technique and the analysis have recently been reviewed in [ 17 ]. The X-ray-generated charge is called the injected charge Q i .…”

Section: Formulation Of the Modelmentioning

confidence: 99%