Effect of Surface Damage on pH Sensitivity of LaAlO₃/SrTiO₃ Heterostructure Device

For solid ion sensors, the sensing surface state plays an important role in the performance, and the processing and testing environment will affect the sensing surface. In this work, the LaTiO 3 /SrTiO 3 heterostructure, an emerging material expected to prepare economical portable and efficient ion sensors, compared the sensing performance device with different sensing thicknesses and different preparation processes. Although these devices show good sensing performance, two noteworthy phenomena are found. The first phenomena are the micromachining process will cause the degradation of device performance; the second is the degree of degradation related to the sensing layer’s thickness. For the device with a 5 unite cells (ucs) thick LAO sensing layer which degradation rate of output current and sensitivity is as high as 91.3% and 91.4%, respectively; for the device with a 7 ucs thick LAO sensing layer which the degradation rate of output current and sensitivity is 59.8% and 34.7%. The surface characterization technique shows that the degradation of the current and sensing performance of devices is caused by surface damage caused by preparation technology. This work provides a research idea for the development of a LaTiO 3 /SrTiO 3 heterojunction sensor and shows the factors affecting the performance of the device, providing an experimental experience for obtaining high-sensing sensitivity devices.