The Design Of Buffer And New Withstand Voltage Structure Of Power ALGaN/GaN HEMT

The third generation wide bandgap semiconductor GaN has been attracted a lotattention for high power and high frequency owing to the superior intrinsic properties ofthe material, such as wide bandgap, high breakdown electric field, high thermalconductance and chemical stabilities.AlGaN/GaN HEMT is one of the GaN-based HEMT devices, which has highdensity of2DEG due to the piezoelectric and spontaneous polarization. AlGaN/GaNHEMT has high power density when compare with Si-and GaAs-based device.AlGaN/GaN HEMT devices have the above advantages, however, the breakdownvoltage of the devices is far lower than the limit value of the material of GaN. So, Thispaper focus on below content to research:AlGaN/GaN HEMT based on RESURF technology is researched, Theconcentration of p-type impurity in the buffer increasing with the gate to drain distance(Lgd), or else the breakdown voltage (Vbr) would be saturated when Lgd>20μm. Afteroptimizing the relationship between the concentration of p-type impurity and Lgd, Theslope of Vbr/Lgdis almost1.6MV/cm and the Vbris not saturated even if Lgd=80μm.Some new structures of AlGaN/GaN HEMT are discussed here, including thebuffer introduced vertical pn junction, the channel of gate’s right introduced P+area, thebarrier of gate’s right introduced super junction. The buffer introduced vertical pnjunction called pn junction composite buffer layer, the principle of this method isintroducing potential well when the pn junction depletion, the buffer leakage could bereduced owing to the electron need extra energy to leave the potential well. Theprinciple of the second method is introducing fixed negative charge at the gate’s right toterminal the electric-power line radio from drain electrode.