High Efficiency Gallium Nitride Based High Electron Mobility Transistors Power Devices And Circuits For Ka-band

In the face of rapid changes in communications industry,the world is constantly connected.From the first transistor application in communication system to VLSI,such as wireless communications,radar,communication,aerospace,military communication and communication space,etc.,all need new semiconductor materials to work with higher voltage,frequency and efficiency.Gallium Nitride materials have series of advantages,such as wider band gap width,higher breakdown electric field,electron saturation rate,high temperature resistance,corrosion resistance,so GaN is suitable for application in the field of high frequency and high power.AlGaN/GaN HEMT devices,with its high concentration of 2DEG,high mobility,high frequency and high power,become the preferred choice for microwave power device.At present,AlGaN/GaN HEMT devices research into the millimeter wave band.High efficiency GaN based high electron mobility transistors power devices and circuits for Ka-band are studied,and the results are as follows:1?The key technology research of ohmic contact.The ohmic contact resistance and contact resistance rate of device with Recess ohmic contact structure,are R_c=0.136?·mm and?_c=4.54×10⁷?·cm²,respectively.The reason for reducing the ohmic contact resistance using this structure,is Recess forming new ohmic contact surface,conducive to the spread of the TiN,formed the second except electron tunneling conductive channel,effectively reduce ohmic contact resistance and contact resistance rate for device.At the same time,the new contact surface is beneficial to increase the contact area,effectively prevent the metal Al spreading on the surface of Au,form a better metal electrode surface morphology.Comparing two kinds of ohmic contact structures,the Recess ohm contact structure can effectively increase the maximum leakage current and reduce the conductance resistance of the device.2?The key technology research of passivation.After dielectric layer of passivation annealing,DC current of device dropped 6.4%.At the same time,annealing devices transconductance is as high as 124 ms/mm.When V_ds=6 v,the cut-off frequency,power gain cut-off frequency and current gain of the annealing device,are f_T=81.8 GHz,f_max=152 GHz and G_max=13.077 dB,respectively.Using the passivation after annealing,helps to reduce the barrier layer surface state density,and improve radio frequency characteristics of the device.At the same time,passivation after annealing also can effectively reduce the reverse leakage current of the device,improve channel current,against current collapse effect bring adverse effects to the device.Therefore,improving the frequency characteristic of the device will be beneficial to its application in the larger field.3?The key technology research of T-type gate with U-type gate foot.The threshold voltage of the device V_th=-1.45 V.Transconductance is as high as 417 mS/mm,compared with convention T-type gate device increase rate of 20%.Meanwhile,T-type gate with U-type gate foot device on/off ratio is I_on/I_off=2×10⁴,conventional convention T-type gate device on/off ratio is I_on/I_off=1.4×10³,compared with convention T-type gate device,T-type gate with U-type gate foot devices have higher power output,better limit threshold characteristics,as well as good power gain.Its application in millimeter wave power device is reflected on the enormous potential.4?Using Win company ka-band GaN HEMT process model library,designed a two level tube power amplifier circuit.The power amplifier circuit is designed in the efficiency of the input power is 29 dBm,and PAE was 10.004%,meanwhile the output power P_out is36.785 dBm,and gain of 7.785 dB.