Ultra-High Sensitivity to Low Hydrogen Gas Concentration With Pd-Decorated IGZO Film

• Published in: IEEE electron device letters Vol. 38; no. 12; pp. 1735 - 1738
• Main Authors: Kumaresan, Yogeenth, Hyeonghun Kim, Yeonggyo Jeong, Yusin Pak, Sungjun Cho, Ryeri Lee, Namsoo Lim, Gun Young Jung
• Format: Journal Article
• Language: English
• Published: IEEE 01-12-2017
• Subjects: carrier concentration; Gas detectors; Hydrogen; Hydrogen sensor; IGZO; II-VI semiconductor materials; palladium; room temperature operation; Sensitivity; Temperature sensors; Zinc oxide
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2017.2765238

To enhance the performance of semiconducting metal oxides, as hydrogen (H 2 ) sensor, we introduced a high carrier concentration (N d ) metal oxide, indium- gallium-zinc oxide (IGZO), combined with palladium (Pd) catalysis. This allowed the detection of low concentrations of H 2 at room temperature. The base current level was linearly increased with the Pd thickness. As a result, a high sensor sensitivity of 6.1 × 10 6 % at 5% H 2 concentration was obtained using a 1-nm-thick Pd-decorated IGZO film. Comparative studies with a zinc oxide (ZnO) counterpart showed that the Nd of IGZO (8 × 10 18 cm -3 ) is significantly higher than that of ZnO (2 × 10 16 cm -3 ), indicating a closer location for the Fermi level of IGZO to the conduction band. Therefore, a relatively small amount of electron-donating H 2 was required to overcome the energy barrier in IGZO. Consequently, the 1-nm-thick Pd-decorated IGZO sensor responded to a gas level as low as 0.01% (100 ppm) and demonstrated a 70-fold higher sensitivity compared with ZnO sensor at all H 2 concentrations.