Gallium Nitride (GaN), remarkably, shows very high electron mobility, wide energy band gap, biocompatibility, and chemical stability. Wurtzite structure makes topmost Gallium atoms electropositive, hence high ligand binding ability especially to anions, making it usable as humidity sensor due to water self-ionization phenomenon. This research is divided into two sections, one is the growth of GaN thin film with improved crystalline quality on low-cost substrate and second one is to utilize it as humidity sensor. Growth parameters of GaN have been studied based on pressure and sputtered gasses ratio by pulsed DC-magnetron Sputtering technique. The crystal quality of GaN is found to improve with decrease in working pressure.

GaN based humidity sensor is fabricated through pulsed modulated...[ Read more ]

Gallium Nitride (GaN), remarkably, shows very high electron mobility, wide energy band gap, biocompatibility, and chemical stability. Wurtzite structure makes topmost Gallium atoms electropositive, hence high ligand binding ability especially to anions, making it usable as humidity sensor due to water self-ionization phenomenon. This research is divided into two sections, one is the growth of GaN thin film with improved crystalline quality on low-cost substrate and second one is to utilize it as humidity sensor. Growth parameters of GaN have been studied based on pressure and sputtered gasses ratio by pulsed DC-magnetron Sputtering technique. The crystal quality of GaN is found to improve with decrease in working pressure.

GaN based humidity sensor is fabricated through pulsed modulated DC magnetron sputtering. Interdigitated electrodes (IDEs) with 100 μm width and spacing were inkjet printed on top of GaN sensing layer to further enhance sensor sensitivity. Simulations were performed to optimize the sensor size and sensitivity responses. Impedance, capacitance, and current response were recorded for humidity and bio-sensing applications. Sensor shows approximate linear impedance response between 0–100% humidity range, very high capacitive sensitivity of ~4380%, and very fast response (T_res) and recovery (T_rec) time of ~3.5 sec and ~9 sec, respectively. Sensor shows very little hysteresis of < 3.53% with stable and wide variations for accurate measurements. Experimental results demonstrate fabricated sensor effectively evaluates plant transpiration through water level monitoring by direct attachment onto leaves without causing any damage as well as freshness level of meat. Superior properties of proposed sensor make it a suitable candidate for future electronics providing low-cost platform for real time monitoring applications.