The VCNR properties of nano-structured ceria thin films

Nano-structured ceria thin films were prepared by using the sol–gel dip-coating method. The films were heated at various temperatures. A constant voltage source is used to measure current–voltage (I–V) properties. We found voltage-controlled differential negative resistance (VCNR) properties in these ceria thin films. The VCNR properties exhibit two distinct characteristics. One is that the VCNR behavior is very obvious for the negative I–V characteristics and is not symmetric about the voltage. The other is that in the negative I–V characteristics region, the current increases sharply at low voltage until it reaches a maximum, and subsequently the current decreases to a minimum but not zero, and then the current continues to rise linearly with increasing of voltage. The conduction mechanism of the above phenomena is discussed and the influence of operating temperature, dopant concentration and heating temperature on the VCNR properties of ceria thin films is analyzed.