Study on a Metal–Insulator–Silicon Hydrogen Sensor With LaTiON as Gate Insulator

In this paper, by using a metal–insulator–semiconductor Schottky-diode structure, we examined the electrical and hydrogen-sensing properties of radio frequency sputtered LaTiON thin films that had been annealed at four different temperatures (450 $^{\circ}{\rm C}$ , 550 $^{\circ}{\rm C}$ , 650 $^{\circ}{\rm C}$ , and 750 $^{\circ}{\rm C}$ ). Characterization of their morphological surface indicates that their average surface roughness decreases from 0.108 to 0.090 nm with increasing annealing temperature. X-ray diffraction shows the growths of La and Ti are in the 1 0 0 direction, i.e., in parallel to the Si substrate. Analysis of measured electrical characteristics indicates that thermionic emission is the dominant mechanism at low temperatures (from RT to 150 $^{\circ}{\rm C}$ ), while Poole–Frenkel emission plays an important role at high temperatures (above 150 $^{\circ}{\rm C}$ ) in the electrical conduction. Results suggest that the sample annealed at 650 $^{\circ}{\rm C}$ has the most promising hydrogen-sensing performance (better current–voltage characteristics, higher sensitivity of 2.0 at 100 $^{\circ}{\rm C}$ ) among the four samples.