Development And Characteristic Analysis Of InAlN/GaN HEMT

As the third-generation semiconductor, GaN has lots of advantages as high breakdown voltage, mobility and saturation velocity and so on. Although the research of AlGaN/GaN HEMT has great development in the past years, the piezopolarization induced by the strain of the lattice mismatched heterostructure is still one of the key problems. At 17% In-content InAlN can be grown lattice matched to GaN, with no piezopolarization, and improve the reliability. But less study have been taken on InAlN/GaN heterostructure in past years, especially this is just the beginning in our state, so this paper will focus on this point.Firstly, this paper presents the InAlN/GaN HEMT with well DC and small-signal characteristics made by ourselves. Then, improve the drain structure and investigate AlGaN/GaN HEMT with schottky drain. This device has significantly high breakdown voltage, and the other characters are as well as common device. Also, the breakdown voltage of this device increases with the schottky barrier height of the drain was studied firstly.Secondly, the trap of the InAlN/GaN HEMT was investigated. Traps on the surface of InAlN were found by the current collapse effect and difference of material sheet resistance after passivation, also the approximate density was calculated by the schottky capacity changed with voltage. These traps were reduced with the method of low temperature anneal. Moerover, the infection of anneal to other characters of device has been analysed.Finally, the heat-temperature characteristics of InAlN/GaN HEMT including surface trap and DC are measured. New traps of surface or barrier were induced by higher temperature, which lead current collapse more serious. Also, the DC peformance and mobility have degenerated for increased temperature, as sheet resistance, contect resiatance, output current and trans-conductance, while the 2DEG has little change.