High sensitivity of halide vapor phase epitaxy grown indium oxide films to ammonia

The effect of H$_2$, NH$_3$, CO and O$_2$ on the electrically conductive properties of In$_2$O$_3$ films grown by halide vapor phase epitaxy has been studied. In the temperature range of 200–550$^\circ$C, In$_2$O$_3$ films demonstrate gas sensitivity to all considered gases, a relatively high operation speed and repeatability of cycles. The greatest response to NH$_3$ was obtained, which exceeded 33 arb. units at a temperature of 400$^\circ$C and a gas concentration of 1000 ppm$^{-1}$. A qualitative mechanism of gas sensitivity of In$_2$O$_3$ films is proposed. The obtained gas-sensitive characteristics are compared with known In$_2$O$_3$ sensors based on various materials. It is shown that the method of halide vapor phase epitaxy makes it possible to obtain indium oxide films with high gas sensitivity.