Trifluoromethane-containing plasma is used to passivate the mesa surfaces and suppresses the surface leakage current of GaN p-i-n rectifiers. Reduction of surface leakage enhances the reverse blocking voltage by 25% measured at J = 1 A/cm 2 . Differential forward resistances of control samples and plasma-treated ones are 0.65 and 0.49 m -cm 2 , respectively, and an excellent Baliga's figure-of-merit of more than 800 MW/cm 2 , as compared with the conventional 545 MW/cm 2 , is achieved for GaN diodes fabricated on sapphire substrates.

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Contact resistivity (ρ C ) reduction for n-SD (source/drain) with Se + implant was evaluated for different integration schemes. It is found that Se + implant energy is one of the most critical process parameters for ρ C improvement, achieved by placing the Se + peak close to silicide (TiSi 2 or NiPtSi)/Si interface and minimized implant damage. Recovery of implant damage to silicide and n-SD region was achieved with millisecond laser anneal, while minimizing dopant deactivation. This work demonstrated a viable integration pathway to realize low ρ C solution for n-SD for 10 nm node.

It is demonstrated that rapid thermal annealing or laser annealing of Mg-doped GaN (about 0.5 μm in thickness) in general helps activate acceptors and increase the average hole concentration by a factor of about 2 from low to mid of 1017/cm3 determined by the Hall measurements. Use of laser annealing of p-GaN coated with Ni and removal afterwards prior to depositing conventional Ni/Au ohmic-contact films, however, greatly improves the contact resistance from 10−2 to 1.6 × 10−4 Ω cm2. Other heat treatment schemes do not improve as much or make it even worse. The most reduction of contact resistance is attributed to the highest surface hole density in an uneven carrier profile achieved by laser annealing with a Ni cap layer.