Selection of non-alloyed ohmic contacts for ZnO nanostructure based devices

摘要

Zinc oxide (ZnO) nanorods were synthesized using a simple and economic aqueous solution method on ZnO coated p-type Si substrates. Their physical properties have been examined using appropriate techniques. These investigations showed that the as-grown ZnO nanorods on ZnO/Si are single crystalline and grown along the [001] direction. These nanostructures exhibited the rms surface roughness and activation energy of approx 16.7 nm and approx 18 meV, respectively. Stable ohmic contacts are essential for reliable operation of any electronic device. To select such contacts for ZnO nanostructures, metal contacts (M velence Ag, Al, In and Sn) were deposited on perfectly cleaned ZnO nanostructures (M/ZnO) using a thermal evaporation technique. From current versus voltage measurements, it is observed that at room temperature the M/ZnO structures except Al/ZnO exhibited nearly ohmic behaviour. With increasing temperature, the contact resistance of all M/ZnO structures except In/ZnO increased due to the formation of metallic bonds between metal and ZnO nanostructures. The annealing effect on M/ZnO structures was also studied, and their behaviour has been discussed and reported.