Impact of oxygen in electrical properties and hot-carrier stress-induced degradation of GaN high electron mobility transistors

The role of the oxygen in AlGaN/GaN high electron mobility transistors(HEMTs)before and after semi-on state stress was discussed.Comparing with the electrical characteristics of the devices in vacuum,air,and oxygen atmosphere,it is revealed that the oxygen has significant influence on the electric characteristics and the hot-carrier-stress-induced degradation of the device.Comparing with the situation in vacuum,the gate leakage increased an order of magnitude in oxygen and air atmosphere.Double gate structure was used to separate the barrier leakage and surface leakage of AlGaN/GaN HEMT it is found that surface leakage is the major influencing factor in gate leakage of SiN-passivated devices before and after semi-on state stress.During semi-on state stress in the oxygen atmosphere,the electric-field-driven oxidation process promoted the oxidation of the nitride layer,and the oxidation layer in the SiN/AlGaN interface leads to the decreasing of the surface leakage.

Electrochemical nitrate reduction to produce ammonia integrated into wastewater treatment:Investigations and challenges

Nitrate(NO_(3)^(-))is widely found in wastewater,which is harmful to human health and water environmental.Electrochemical reduction can convert NO_(3)^(-)to high value-added ammonia(NH)3)/ammonium(NH_(4)^(+))for pollutant removal and resource recovery.Currently,electrochemical nitrate reduction to produce ammonia(ENRA)is mostly focused on the preparation of high-performance catalysts,while ignoring the prerequisite for industrial application as the stable operation and optimal regulation of the process.Therefore,the review focused on wastewater treatment,based on the mechanism of electrochemical nitrate reduction for ammonia production and reactor construction(reactor,power supply system),then summarized the operation control strategies(such as reduction potential,nitrate concentration,inorganic ions,p H)that should be noted for ENRA.Finally,the challenges(system structure,economy)and prospects(ammonia recovery process,construction of large-scale ENRA system,application of real wastewater)of the field as it moves towards commercialization were discussed.It is hoped that this review will facilitate the scaling up of ENRA in the wastewater treatment field.