TMAH-based wet surface pre-treatment for reduction of leakage current in AlGaN/GaN MIS-HEMTs

다국어 초록 (Multilingual Abstract)

The pre-passivation surface treatment process with tetramethylammonium hydroxide (TMAH)-based wet solution was proposed for the minimization of the leakage current (I<SUB>leak</SUB>) in AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs). This process step contributes to the simultaneous decrease of the surface current (I<SUB>surf</SUB>) in the active region of device and mesa-isolated region by removing the surface states and traps related to nitrogen (N) vacancy, Ga-oxide, and dangling bonds. Using the surface treatment, the fabricated device achieves a lower off-state current (I<SUB>off</SUB>) of ~10<SUP>-12</SUP>A/mm, a higher on/off current ratio (I<SUB>on</SUB>/I<SUB>off</SUB>) of ~10<SUP>11</SUP>, a small subthreshold swing (SS) of 68.4mV/dec. The reduced I<SUB>leak</SUB> also improves breakdown voltage (BV). In addition, the interface trap density (D<SUB>it</SUB>) between the SiN layer and the AlGaN surface was extracted to evaluate the quality of the SiN/GaN interface, which showed that the treatment decreases the D<SUB>it</SUB> with reduction of the surface defects.