Schottky-Richardson emission

However, experimental ]V curves often deviate from the ideal /scl- In these cases, the measured current /inj is injection limited caused by a nonohmic contact or poor surface morphology. When the MO interface is nonohmic, carrier injection can be described by the Richardson-Schottky model of thermionic emission the carriers are injected into organic solid only when they acquire sufficient thermal energy to overcome the Schottky barrier ((()), which is related to the organic ionization potential (/p), the electron affinity (AJ, the metal work function (O, ), and the vacuum level shift (A) [34,35]. Thus, the carrier injection efficiency (rj) can be calculated by the following equation ... 

Schottky (1914) emission is governed by the Richardson-Schottky equation of thermal emission over the image-force barrier... 

To study charge injection mechanisms, we have tried to fit Richardson-Schottky thermionic emission and Fowler-Nordheim tunnelling mechanisms. We have found that under forward bias, the temperature-independent Fowler-Nordheim (FN) tunnelling mechanism is applicable, which presumes tunnelling of charge carriers directly into the bands of the semiconductor. According to the model, the current density J) is related to the applied field F) as [11,12] ... 

Under reverse bias, the FN tunnelling mechanism did not apply. On the other hand, the current-density was found to follow Richardson-Schottky thermionic emission model, where tunnelling through the barrier is ignored and field-induced barrier lowering is taken into consideration. The current density at a temperature T is given by [13] ... 

One of the techniques for measuring the work function of surfaces uses the thermal emission of electrons from the heated surface under study [4]. According to the Richardson-Schottky equation, the electron current density, I, depends on the surface temperature, T, and the work function, / ... 

The current density jj s for this process, which at high temperatures is also called glow emission, was originally calculated by Richardson for glow cathodes in vacuum valves and, taking the Schottky effect into account, is given by ... 

In the presence of an applied electric field, the barrier profiles ate altered. If the applied field is high enough and the electrode makes ohmic contact with the dielectric, then the charge carriers are bjected bto the insulator by lowering the barrier of metal-insulator bterface. This effect is known as Schottky-Richardson (S-R) cmissbo. The expression for the current due to S-R emission is given by... 

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