Pulse transient method used for analysis of temperature modulated space charge limited currents

conference paper

English

Space charge limited currents (SCLC) plays a key role in studies of the localised energy states distribution into a forbidden energy band gap of inorganic and/or organic semiconductors. The shape (slope) of the current-voltage characteristics reflect the amount of trapped electrons (holes) injected into the semiconductor on the change of the Fermi energy level [1, 2]. Utilising the temperature modulated space charge limited current (TM SCLC) characteristics it began to be possible to determine the energetic position of the states responsible for the electron (hole) trapping [3, 4, 5]. The method was used as a semistationary: the measurement was performed as a slow temperature wobbling near the room temperature. However, the method fails when the activation energies are low (~kT) because the experimental error of the steepness determination from the Arrhenius dependence of electric current (ln I = f(1/T)) significantly increases in this region. In this contribution, we present a modification of the method that does not suffer such drawback. It is based on pulse transient method conventionally used to determine heat properties (diffusivity, thermal conductivity, specific heat) [5, 7]. From the time-dependence of the electric current it is possible to both, find a window with current modulated by temperature change, but in particular, to determine the activation energy of the current, even thus is the current change very low (so-called Child's law). If higher activation energies are present, it is possible to determine the behaviour of the measured semiconductors for several temperatures.

space charge limited current, transient method

ZMEŠKAL, O.; ŠTEFKOVÁ, P.; VALA, M.; WEITER, M.

2006

13. 10. 2006

STU Bratislava

Kočovce

80-227-2536-6

Thermophysics 2006

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