Research On High-power GaN Microwave And Millimeter Wave Diode And Circuit

With the continuous development of wireless technology,application scenarios such as high-power microwave wireless power transmission and high-performance limiter have put forward higher and higher requirements on core components,microwave diodes.The development of traditional semiconductor materials such as Siand GaAs is facing a bottleneck and cannot meet the requirements of related applications.The third-generation semiconductor material GaN has a larger band gap and higher breakdown field.Inparticular,its heterojunction material generates high-density two-dimensional electron gas（2DEG）due to strong spontaneous polarization and piezoelectric polarization,and has excellent characteristics such as high electron mobility and high electron saturation speed.GaN microwave diodes are expected to bring revolutionary breakthroughs in power and frequency.However,compared with GaN microwave HEMT devices,GaN microwave diodes and their applications are less researched,and still have huge development potential,which requires systematic and in-depth research.Based on the above background,a series of research on the device fabrication,structure optimization,characterization and related application development of GaN microwave diodes are carried out.The detailed work and research results are summarized as follows:1.A lateral GaN microwave diode structure with a low work function W metal recessed anode is proposed.Key processes such as low-damage and slow-rate anode recess etching,Al₂O₃ film surface passivation,secondary composite passivation have been developed to produce high performance SiC-based AlGaN/GaN microwave diodes.GaN rectifier module and microwave power transmission system operating at 2.45 GHz is developed.The diode achieves a low turn-on voltage of 0.47 V,a low zero bias junction capacitance of 0.427pF/mm,and device with a cathode-anode spacing of 3μm achieves a low on-resistance of3.02Ω·mm,a high breakdown voltage of 170 V,a cut-off frequency of up to 124 GHz,and a Johnson quality factor（BV×f _T）of up to 21 THz·V,which is at the international advanced level.The 2.45 GHz GaN rectifier module achieves a peak conversion efficiency of 79%at input power of 28.64 dBm and maintained efficiency higher than 50%at 37.33 dBm.Its power capacity is 10-50 times that of traditional Sirectifier modules,reaching the international advanced level.The 2.45 GHz microwave power transmission system successfully realized the transmission of 1.4 W DC power at a distance of 1.5 meters.2.Inview of the limitation of device current collapse on high-frequency applications,LPCVD-grown SiN high-quality surface passivation,low-k dielectric secondary passivation,composite global passivation and other processes have been developed to fabricate low-current collapse SiC-based AlGAN/GaN microwave diodes and realize commercialization.GaN microwave rectifier modules and power transmission systems operating at 5.8 GHz have also been developed.The diode has a lower turn-on voltage of 0.38 V,a low zero bias junction capacitance of 0.43 pF/mm,a device with a cathode-to-anode spacing of 3.5μm has a low on-resistance of 3.4Ω·mm,a high breakdown voltage of 164 V and a high cut-off frequency of 110 GHz,and after applying-100 V reverse stress for 10 seconds,the on-resistance degradation is reduced by 8%.The SiN/SiO₂/SiN composite global passivation process was developed,and after the device applying-100 V reverse stress at 150℃for 1hour,the on-resistance increased by only 2.94 times.Through this technology,gallium nitride microwave diodes on 4-inch epitaxial wafers have been commercialized.The 5.8GHz GaN microwave rectifier module achieves a peak efficiency of 72.3%at 2.5 W input power and a 50%conversion efficiency at 5.4 W,which is the best in the world for the same period.The 5.8 GHz GaN microwave energy transmission system achieves energy at a distance of 2 meters.transmission.3.Developed high-performance and low-cost silicon-based AlGaN/GaN microwave diodes and 2.45 GHz silicon-based GaN microwave rectifier modules.Diode with a cathode-to-anode spacing of 2μm has turn-on voltage of 0.36 V,series resistance of 1.53Ω·mm,zero-bias junction capacitance of 0.55 pF/mm,high breakdown voltage of 132 V,cut-off frequency as high as 190 GHz and the Johnson quality factor of this diode reaches 25.1THz·V.The device has a breakdown voltage greater than 100 V and a forward switching ratio of 10⁴ even at a high temperature of 300℃.The GaN-on-silicon microwave rectifier achieves a peak efficiency of 71.6%under an input signal of 2.45 GHz and 31.23 dBm,and the performance in the high-power range of this module is compatible with SiC-based GaN microwave rectifier modules.4.In response to high-power microwave limiter requirements,a passive limiting circuit based on GaN Schottky diodes was designed.A self-aligned recessed anode GaN millimeter wave diode structure using high work function anode metal Pt was developed.With key process such as self-aligned anode,a high-performance SiC-based InAlN/GaN millimeter wave diode for limiter has been developed.The diode has a turn-on voltage of 0.98 V and a low zero-bias junction capacitance of 0.21 pF/mm,the 2μm cathode-anode spacing device achieves on-resistance as low as 1.24Ω·mm,breakdown voltage and cut-off frequency are as high as 124 V and 600 GHz,respectively,and Johnson quality factor is 74.4 THz·V,which is at the international leading level.Based on this technology,it is expected to realize the X-band 50 W continuous wave limiter.