Nonlinear I–V characteristics of doped SnO2

When tin oxide is doped with Sb2O3 and CoO, it shows highly nonlinear current (I)–voltage (V) characteristics. Addition of CoO leads to creation of oxygen vacancies and helps in sintering of SnO2. Antimony oxide acts as a donor and increases the conductivity. The results are nearly same when antimony oxide is replaced by tantalum oxide. The grain size of these sintered ceramics varies from 5 to 7 μm and the grain boundary barrier height (ΦB) is in the range of 0.5 eV. The observed nonlinear coefficient (α) is 25 and 27 for antimony and tantalum oxide, respectively and the breakdown field is in the range of 1250 V cm−1.