TSDCs in Se-Based Amorphous Semiconductors Experimental Results

3 TSDCs in Se-Based Amorphous Semiconductors Experimental Results 

TSDC experiments are customarily analyzed assuming the sample behaves ohmic, i.e., the contacts do not introduce an inhomogeneous distfibution of the electric field or carrier density and a uniform bulk density of carriers extend through the entire sample. Experiments were carried out in such a way as to minimize injection effects. Contact configuration was typical for TSDC experiments. Because the currents through the sample are, in almost aU cases, extremely small, we have used a sensitive DC ammeter (model Ul-15, detection limit 10 A) with a hnear output signal. The simplest way to obtain a record of TSDC is an X-Y recorder that displays I(T) and the temperature. The equipment for the extraction of trap-spectroscopic information may be connected with devices for electronic data processing. The experimental errors in determination are less than 2%. 

In the TSDC considered here, a sample is cooled to a low temperature ( 100K) and illuminated with 3 X 10 lx hght for a time tp ( 4min) in the presence of an applied DC field (E = 5 X 10 V/cm). Then, the light and voltage are switched off the structure is short-circuited and, after a delay period necessary for sample relaxation (to reach equihbrium between the free and the trapped carriers), the sample is heated in the darkness at a constant rate Vt while the TSDC is measured. We preferred TSDC experiments because of the absence of noise due to a voltage source and the strongly reduced influence of the intrinsic conductivity. 

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