Research On AlGaN/GaN MOS-HEMT Device With High-K Dielectric

Due to its advantages in high-frequency and high-power applications,GaN HEMT devices have become a research hotspot.However,AlGaN/GaN HEMT devices with Schottky gate electrodes suffer from problems such as high gate leakage,small gate voltage swing and current collapse,which seriously limits their practical applications.By inserting an insulator between the gate and AlGaN to prepare a MOS HEMT,the above problems can be effectively improved.Furthermore,the high K dielectric has a greater permittivity.When inserted as an insulating layer,the MOS HEMT will lose less gate control capability while maintaining a low gate leakage current,so it is of great research significance.Based on this,this work mainly studies MOS-HEMT devices with Hf O₂ gate dielectric deposited by magnetron sputtering and Y₂O₃gate dielectric prepared by the thermal oxidation.The main contents are as follows:1?Firstly,the process condition of the Hf O₂ film deposited by magnetron sputtering were optimized,and the optimized thin film with a breakdown field strength of 6.135 MV/cm was prepared.The film was subsequently applied to AlGaN/GaN MOS-HEMT devices.In view of the sputtering process causing damage to the AlGaN surface,which results in device performance degradation.This work systematically studies the effects of different PDA(post-dielectric annealing)conditions on the I-V characteristics,interface characteristics and current collapse characteristics of the device,and obtains an optimized PDA processing technology to improve the device performance.it is found that the samples treated at 400?-10min have the best I-V characteristics,and the output current and peak transconductance are 3.98 times and2.56 times higher than those of samples without post-deposition annealing.The breakdown voltage is as high as 573V.Through the C-V test and the transfer pulse I-V test,the interface state distribution information of the samples with different post-deposition annealing is obtained.It is found that as the temperature of post-deposition annealing treatments increases,the interface state density will decrease.The passivation effect of the samples treated with different PDA was analyzed by double-pulse current collapse test.It was found that with the increase of PDA temperature,the current collapse inhibition ability of Hf O₂ films increased.Comprehensive considerations show that the best device characteristics can be obtained after post-deposition annealing at 400?-10min.2?The Y₂O₃ gate dielectric film is prepared by thermal oxidation and applied to AlGaN/GaN HEMT devices.By analyzing the I-V characteristics,interface characteristics and current collapse characteristics of MOS-HEMT devices with Y₂O₃ gate dielectric prepared by different thermal oxidation process,the variation rules with different thermal oxidation temperature of characteristic parameters such as gate leakage,saturated output current,transconductance,interface state and current collapse of Y₂O₃ MOS-HEMT device were obtained.Finally,it is concluded that the MOS-HEMT with Y₂O₃ gate dielectric prepared by thermal oxidation at 500?-10min has best I-V characteristics,and the MOS-HEMT with Y₂O₃gate dielectric prepared by thermal oxidation at 400?-10min has best interface characteristics and current collapse characteristics.