Solid-State Electronics, Vol.141, 13-17, 2018
Normally-off Al2O3/GaN MOSFET: Role of border traps on the device transport characteristics
Based on the self-terminating gate recess technique, two different processes featuring gate-recess-first (GF) and ohmic-contact-first (OF) were proposed for E-mode Al2O3/GaN MOSFETs. Increased maximum drain current (I-dmax) similar to 30% (420 vs 325 mA/mm), field-effect mobility (mu(FEmax)) similar to 67% (150 vs 90 cm(2)/Vs) and reduced on-state resistance (R-on) similar to 42% (9.7 vs 16.8 Omega.mm) were observed in the devices fabricated by GF process. Such significant performance difference of GF- and OF-devices resulted from the presence of border traps at Al2O3/GaN interface with a time constant similar to 7 x 10(-6) s. Experimental results indicated that (1) the near interface border traps in Al(2)O(3)dielectric significantly affect device channel mobility; (2) a high temperature post-de-position annealing process could effective suppress generation of border traps.