Electric field measurements in stationary and moving high-field domains in cadmium sulphide

A procedure is described how the negative differential conductivity (NDC) of copper‐doped CdS single crystals can be calculated from the measured distribution of the electric field strength between the electrodes in the case of current‐voltage saturation. From that the ratio between free and trapped electrons can be evaluated. The mechanism of saturation and the boundary conditions of the corresponding differential equations are discussed in detail. A reaction kinetic relation which explains both the current‐voltage saturation and the current–generation‐rate saturation of the samples is shown.

Current-voltage saturation in copper-doped CdS single crystals and calculation of the negative differential conductivity

Heinz¹

1974

Experimental examination of the field-enhanced thermal emission of holes in CdS

Junker¹,

Heinz²

1974

Self Cite

The negative differential conductivity (NDC) of copper doped CdS single crystals was measured under various experimental conditions as different optical excitation rates, additional optical quenching, and different temperatures between liquid air and room temperature. It is shown that there is no influence on NDC from generation or quenching. Also the critical electric field strength where NDC sets in suddenly, does not depend on temperature. Only a t higher fields there is ti NDC dependence on temperature. It is shown that this behaviour fits very well to a modified model of the field enhanced thermal emission of trapped holes.Die negative differentielle Leitfahigkeit (NDC) von kupferdotierten CdS-Einkristallen wurde unter verscliiedenen Versuc:hsbedingungen wie verschiedenen Anregungsraten, zusatzliche optische Tilguiig und varschiedenen Temperaturen zwischen fliissiger Luft-und Zimmertemperatur gemessen. Es wird gezeigt, daB die NDC von der Anregungs-und Tilgungsrate nicht beeinflu& wird, und daD die kritische Yeldstarke, bei der die NDC plotzlich einsetzt, auch nicht von der Teinperatur abhangt. Erst bei hijherer Feldstarke wird die NDC-Abhangigkeit durch die Temperatur verandert. Es wird gezeigt, daB dieses Verhalten sehr gut mit einem modifizierten Model1 der feldbegiinstigteii thermischen Emission von Lochern aus Haftstellen iibereinstimmt.

A new type of electrical instability in CdS

Gilbert

Hoffmann

1975

A new type of current oscillatioris in the range of to 10 Hz lias been observed in illuminated CdS single crystals with electron conccntrat'ions in the order of 1 O7 t o 1O1OThese instabilities havc been observed a t field strengths as low as 6 x 10' V em-1 with and withont additional quenching light. Furthermore, there is no region of ncgativc differential condrictivity in the I-U-charact,eristic. Es Tvird iibcr eineri rieuen Typ von Stronioszillntionen in1 Bereicli voii his 10 Hz berichtet, dcr in bclichteten CdS-Einliristalleri mit Elekt.roncnkonzeiit,rationeri von lo7 his 1U'O cmr3 beobnclitet murde. Diese Jnstabilit6tc.n wurden niit nnd ohne znsiitzliclies Tilgungslicht schon bei FcldstSrken oberhbal von 5 x 10' V c1ii-l beobachtct. Ferner hat die Strorn-Spannungs-Keiinlinie lzeinen Bereich m i t negativer differenticllcr Lzitfiihigkeit.