Performance of GaN MESFETs with an undoped highly resistive buffer layer

In this paper, we report on the DC and RF performances of recessed gate GaN MESFETs fabricated using an undoped highly resistive buffer layer. The per formance of the device is found to be significantly improved compared with that of a device with an Mg-doped p(-)-GaN buffer layer. The performance im provement stems from the resistance of an undoped layer being higher than t hat of a p(-)-GaN buffer layer. The GaN MESFET fabricated with an undoped h ighly resistive layer exhibits a current saturation at V-DS = 4 V and V-GS = 0 V and a pinch-off at V-GS = -3 V. The peak drain currents of the device are about 230 mA/mm and 215 mA/mm at 300 K and 473 K, respectively The roo m temperature f(T) and f(max) from the device are 6.35 GHz and 10.25 GHz, r espectively. A physics-based analytic model was applied and found to be use ful for predicting the DC performance of the GaN MESFET.