Characteristics of GaN-Based Nanowire Gate-All-Around (GAA) Transistors.

We investigate the DC, C-V , and pulse performances in GaN-based nanowire gate-all-around (GAA) transistors with two kinds of geometry: one is AlGaN/GaN heterostructure with two dimensional electron gas (2DEG) channel and the other is only GaN layer without 2DEG channel. From I-V and C-V curves, the fabricated GaN nanowire GAA transistor with AlGaN layer clearly exhibits normally-on operation with negative threshold voltage ( V _th ) due to the existence of 2DEG channel on the trapezoidal shaped GaN nanowire. On the other hand, the GaN nanowire GAA transistor without AlGaN layer presents a positive V _th (normally-off operation) due to the absent of 2DEG channel on the triangle shaped GaN nanowire. However, both devices show the similar temperaturedependent I-V characteristics due to the combination of bulk channel and surface channel in GaN nanowire GAA channel are mostly contributed, rather than the 2DEG channel. GaN-based nanowire GAA transistors demonstrate to almost negligible current collapse phenomenon due to the perfect GAA gate structure in GaN nanowire. The proposed GaN-based nanowire GAA transistors are very promising candidate for both high power device and nano-electronics application.