The Effect of an Fe-doped GaN Buffer on off-State Breakdown Characteristics in AlGaN/GaN HEMTs on Si Substrate

An Fe-doped GaN buffer layer was employed in the growth of AlGaN/GaN high-electron mobility transistors (HEMTs) on Si substrates. In order to investigate the effects of an Fe-doped GaN buffer on OFF-state breakdown characteristics, HEMT devices with an Fe-doped GaN buffer on Si substrates were fabricated along with conventional devices utilizing an unintentionally doped GaN buffer on Si substrates. The device characteristics were compared. While HEMT devices with the conventional structure showed an extremely unstable OFF-state breakdown behavior due to punchthrough to the Si substrate, it was demonstrated that an Fe-doped GaN buffer layer on a Si substrate successfully suppressed the premature failure caused by Si-induced breakdown. As a result, the AlGaN/GaN HEMTs with an Fe-doped GaN buffer on Si substrates exhibited much more consistent and enhanced breakdown voltages, when compared with the conventional devices. Consequently, it is highly desirable that AlGaN/GaN HEMTs on Si substrates have an Fe-doped GaN buffer layer in order to achieve stable and robust OFF-state breakdown characteristics