We deposited a thin ZnO film on P-Type silicon wafers by sol-gel spin coating using gold as a metal contact. We have found the thin films were composed by nano particles. As shown in the figure, the temperature dependence of I-V shows ohmic contact at low voltage and Schottky contact at higher voltage. Can someone explain this phenomena? Why do both of them (ohmic and Schottky contact) happen for a single sample? We have used 4-point probe for I-V characterization.
Hi Kevin,
The current changing from Linear to Nonlinear is normally found in Organi diodes, where the Organic material is sandwiched between two nearly same work function metals. For low applied voltages the current is governed by the bulk property of the material whereas for higher voltages the space charge accumulated inside the device changes the current to space charge limited current (SCLC) which typically varies nonlinearly with the applied voltage. Can you confirm the nature of current in the higher forward bias whether it is exponential or non-linear?
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