Ghosh Sugato, Bhattacharyya Raghunath, Saha Hiranmay, Chaudhuri Chirasree Roy, Mukherjee Nillohit
Centre of Excellence for Green Energy and Sensor Systems, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103, West Bengal, India.
Phys Chem Chem Phys. 2015 Nov 7;17(41):27777-88. doi: 10.1039/c5cp04947d.
Metal oxide semiconductors have been extensively used as reducing gas sensors with major limitations regarding selectivity and operating temperature which is relatively high for most of the cases making the device unusable in some critical situations. Higher operating temperature is also associated with the higher power consumption, which goes against the miniaturization of the device. In order to resolve these problems, here we introduced a ZnO/ZnO2 straddling 'n-N' isotype heterostructure as a highly selective and sensitive methane sensor at moderately low operating temperature. ZnO-Zn(OH)2 precursor films were treated in oxygen plasma in a pulsed DC magnetron sputtering system. Morphological analyses by field emission scanning electron microscopy showed flake like growth of the grains with high surface roughness, whereas X-ray diffraction (XRD) showed polycrystalline nature of the films. Polycrystalline ZnO2 peaks were observed in the XRD pattern in addition to the existing ZnO, which indicates modification of the precursor to oxygen rich heterostructure of ZnO/ZnO2. This was further supported by the shifting of the O1s peak in the X-ray photoelectron spectroscopic analysis. Plasma treated ZnO/ZnO2 heterostructured films were found to show high selectivity towards methane (with respect to H2S and CO) and sensitivity (∼96%) at a comparatively low operating temperature.
金属氧化物半导体已被广泛用作还原性气体传感器，但存在选择性和工作温度方面的主要局限性，在大多数情况下工作温度相对较高，这使得该器件在某些关键情况下无法使用。较高的工作温度还与较高的功耗相关，这不利于器件的小型化。为了解决这些问题，我们在此引入了一种ZnO/ZnO₂跨接的“n-N”同型异质结构，作为一种在适度低温下具有高选择性和高灵敏度的甲烷传感器。ZnO-Zn(OH)₂前驱体薄膜在脉冲直流磁控溅射系统中进行氧等离子体处理。场发射扫描电子显微镜的形态分析表明，晶粒呈片状生长，表面粗糙度较高，而X射线衍射(XRD)表明薄膜具有多晶性质。除了现有的ZnO外，在XRD图谱中还观察到了多晶ZnO₂峰，这表明前驱体已改性为富含氧的ZnO/ZnO₂异质结构。X射线光电子能谱分析中O1s峰的位移进一步证实了这一点。发现经等离子体处理的ZnO/ZnO₂异质结构薄膜在相对较低的工作温度下对甲烷（相对于H₂S和CO）具有高选择性和灵敏度（约96%）。
