Abstract
We have demonstrated AlGaN/GaN HEMTs with lightly-doped buried p-layers under the channel for the first time. A 2-μ-gate device showed good pinch-off characteristics, gm of 55mS/mm, and breakdown voltage of 70_??_90V. It was confirmed that the p-n junction successfully suppressed leakage current under the channel, and the ohmic metallization did not penetrate to the buried p-layer. Carrier confinement by the p-n junction was confirmed by both one-dimensional calculations by solving the Poisson equations and capacitance-voltage measurements. As for RF performances, the maximum fr of 5.5GHz and a carrier velocity of 1×107cm/s were obtained. These results indicate the potential of p-layer insertion into GaN-based FETs for reducing a short-channel effect and possibility of impact ionization. We can conclude that p-layers can be applied to GaN FETs in the same manner that they are to III-V semiconductor electron devices.
