Profiling of hydrogen in metal-insulator-semiconductor sensors using neutron reflectivity

Although interfacial hydrogen has long been accepted as the species responsible for $H2$ detection in metal-insulator-semiconductor (MIS) sensors, direct observation of this species has been elusive. In this work, the use of neutron reflectivity (NR) to quantify the hydrogen concentration in regions of an MIS device is reported. The presence of multiple states at both the metal-insulator interface and within the insulator that may contribute to the hydrogen response is suggested by the scattering length density profiles obtained from NR. This technique provides a great promise for direct study of the detection mechanisms for MIS sensors.