Research On Si-based GaN RF Device

GaN HEMT RF devices are widely used in microwave and millimeterwave wireless communication fields owing to their excellent frequency and power characteristics.Among them,Si-based GaN RF devices have gradually become the popular direction of technological development due to their cheap price and great compatibility with Si CMOS.This paper mainly presents the development trend,basic working principles of Si-based GaN devices,and focuses on the research of material structure design,device preparation process and performance analysis.Finally the research results obtained are as follows:(1)The impact of the growth process of GaN buffer on the RF loss of Si-based GaN heterojunction is explored.The Si-based GaN HEMT obtains a low RF loss of 0.72 dB/mm by guiding the optimization of epitaxial growth process.(2)The ohmic alloy process of traditional GaN HEMT devices is improved by introducing a bottom metal or replacing the Ni barrier layer.Finally,the contact resistance of the device is reduced and a smoother surface morphology is obtained.(3)The Si-based GaN microwave devices with 0.4 ?m and 0.25 ?m gate length are developed which achieve great breakdown characteristics and thermal stability thanks to the V-shaped refractory metal barrier structure.According to the test,the device with 0.25 ?m gate length can realize the power gain of 12.3 dB,the Pout of 3.6 W/mm,and the PAE of about 45%at 10 GHz.(4)Based on the T-gate structure,the Si-based GaN millimeterwave devices with 50 nm and 100 nm gate length are developed.In addition,the suppression effect of A12O3 passivation layer on the current collapse is analyzed.After passivation,the fT/fmax of the device with 50nm gate length can reach 134 GHz and 280 GHz respectively.In summary,this issue exhibits a detailed and structured research on the Si-based GaN RF devices.The performance of the Si-based GaN RF devices is optimized from two aspects:material structure and device process.Finally,the Si-based GaN RF devices of different processes are developed,laying the foundation for its large-scale production and application.