AlGaN/GaN Superlattice-Based p-Type Field-Effect Transistor with Tetramethylammonium Hydroxide Treatment

To realize the full spectrum of advantages that the III-nitride materials system offers, the demonstration of p-channel III-nitride-based devices is valuable. The first p-type field-effect transistor (pFET) based on an AlGaN/GaN superlattice (SL), grown using metal-organic chemical vapor deposition (MOCVD), is reported. Magnesium is used as the p-type dopant. A sheet resistance of 11.6 k omega (-1) and a contact resistance of 14.9 omega mm are determined using transmission line measurements (TLMs) for Mg doping of 1.5 x 10(19) cm(-3). Mobilities in the range of 7-10 cm(2) (V s)(-1) and a total sheet charge density in the range of 1 x 10(13)-6 x 10(13) cm(-2) are measured using room temperature Hall effect measurements. Without tetramethylammonium hydroxide (TMAH) treatment, the fabricated pFETs have a maximum drain-source current (I-DS) of 3 mA mm(-1) and an on-resistance (R-ON) of 3.48 k omega mm and do not turn off completely. With TMAH treatment during fabrication, a maximum I-DS of 4.5 mA mm(-1), R-ON of 2.2 k omega mm, and five orders of current modulation are demonstrated.