Research On AlInN Schottky Diode And AlInN Electrochemical Sensor

GaN-based materials possess large band gap,high electron mobility and good stability and other advantages.GaN-based High Electron Mobility Transistor(HEMT)structure are very attractive for microwave communications,high-power application and so on.One advantage of GaN-based materials is the ability to form many kinds of heterostructures.The AlGaN/GaN heterostructure is widely used because of the existence of two-dimensional electron gas with high concentration and high mobility induced by spontaneous and piezoelectric polarization.In recent years,the lattice matching AlInN/GaN hetero structure attracts lots of research by providing a high concentration of two-dimensional electron gas without piezoelectric polarization which is a big adventage in many fields.This paper studied the influence ICP oxidation brought to AlInN Schottky diode and developed a AlInN electrochemical sensor based on non-gate HEMT structure.Metal-insulator-semiconductor(MIS)structure can achieve low leakage current and have high breakdown voltage.There have been many studies on the preparation of the insulating layer in MIS structure,but few studies have been made about preparing MIS structure using ICP.ICP etching is a common process for preparing GaN-based devices,if it can also be used in plasma oxidation to form insulating layer will simplify the process.We use ICP to oxide AlInN surface then fabricate Schottky diode.XPS analysis conforms there is an oxidation layer formed on AlInN surface,but the ?-? measurement shows a instable current characteristics for ICP treated sample.In the first time test,the treated sample's reverse leakage current was suppressed by three magnitudes,but in repeated test the leakage current raise back up to the same level as the untreated sample.We used a variety of current transport models to fit the measured currentand assumed that defects induced by ICP treatment whose charging and discharging process is related to this abnormal phenomenon.We also proposed a model based on a nitrogen vacancy defects to explain the abnormal current.The defect level is located above the Fermi level and only in the forward voltage sweep will the defect traps capture electrons,these electrons will be released when reverse voltage sweeps which increases the leakage current.This model can well explain the observed results.GaN-based material has good chemical stability and is suitable for preparing electrochemical sensors.We developed a AlInN electrochemical sensor based on HEMT structure which can be used in water negative ion examination.The principle of this sensor is to form a polymer molecular film using ion imprinting technology on the gate region as functionalization,once molecular film captures ion that need to be detected the potential of the gate region will affect the concentration of channel electrons,through the changes of the source-drain current It can be determined whether detected this ion or not.Because using the AlInN thin barrier,the sensitivity of the sensor can be higher than the same type AlGaN sensor.Through detecting different negative ion we discovered the sensor using ion imprinting has a good ion-selective.