  Nanocomposite metal oxide thin films exhibit assuring qualities in the field
of gas sensors because of the collective opportunities provided by the
heterointerface formation. In this work, we present the synthesis of nitrogen
doped mesoporous In$_2$O$_3$-ZnO nano-composite thin films by simple wet
chemical method using urea as the nitrogen precursor. SEM investigation
suggests formation of mesoporous nano-composite thin films, where the
uniformity of surface pore distribution depends on the relative proportion of
In$_2$O$_3$ and ZnO in the composites. HRTEM investigation suggest formation of
sharp interfaces between N-In$_2$O$_3$ and N-ZnO grains in the nano-composite
thin films. The nano-composite thin films have been tested for their ethanol
sensing performance over an extensive range of temperature, ethanol vapor
concentration and relative humidity. Nitrogen doped nano-composite thin film
with equal proportion of In$_2$O$_3$ and ZnO exhibits excellent ethanol sensing
performance at a reasonable operating temperature (~94 % at 200 {\deg}C for 50
ppm of ethanol), fast response time (~two seconds), stability over time,
enhanced resilience against humidity and selectivity to ethanol over various
other volatile organic compounds.
