Abstract-Conventional GaN vertical devices, though promising for high-power applications, need expensive GaN substrates. Recently, low-cost GaN-on-Si vertical diodes have been demonstrated for the first time. This paper presents a systematic study to understand and control the OFF-state leakage current in the GaN-on-Si vertical diodes. Various leakage sources were investigated and separated, including leakage through the bulk drift region, passivation layer, etch sidewall, and transition layers. To suppress the leakage along the etch sidewall, an advanced edge termination technology has been developed by combining plasma treatment, tetramethylammonium hydroxide wet etching, and ion implantation. With this advanced edge termination technology, an OFF-state leakage current similar to Si, SiC, and GaN lateral devices has been achieved in the GaN-on-Si vertical diodes with over 300 V breakdown voltage and 2.9-MV/cm peak electric field. The origin of the remaining OFF-state leakage current can be explained by a combination of electron tunneling at the p-GaN/drift-layer interface and carrier hopping between dislocation traps. The low leakage current achieved in these devices demonstrates the great potential of the GaN-on-Si vertical device as a new low-cost candidate for high-performance power electronics.Index Terms-Edge termination, GaN-on-Si vertical device, leakage control, leakage origin, power electronics.
Heavily carbon-doped In 0.53 Ga 0.47 As on InP (001) substrate grown by solid source molecular beam epitaxyThe effect of thermal annealing on the net donor concentration and diffusion of Si in In 0.53 Ga 0.47 As is compared for electrically active layers formed by ion implantation versus molecular beam epitaxy (MBE). Upon thermal treatment at temperatures of 700 C or higher for 10 min, both ion implanted and growth-doped substrates converge to a common net donor solubility. These results indicate that while MBE doped substrates typically exhibit higher active concentrations relative to implanted substrates, the higher active Si concentrations from MBE growth are metastable and susceptible to deactivation upon subsequent thermal treatments after growth. Active Si doping concentrations in MBE doped material and ion-implanted materials are shown to converge toward a fixed net donor solubility limit of 1.4 Â 10 19 cm À3 . Secondary ion mass spectroscopy of annealed samples indicates that the diffusivity of Si in MBE doped substrates is higher than those of ion implanted substrates presumably due to concentration-dependent diffusion effects.
A brief review of n-type doping of GaAs, InGaAs and InP using ion implantation is presented. While the diffusion of the amphoteric dopant Si is not a significant issue its activation is limited to around 1×1019/cm3. This has prompted many studies into factors that might affect dopant activation including co-implantation to force site selection, damage and amorphization effects, elevated temperature implants and capping effects. A summary of these results is discussed. With interest in using III-V materials for n-channel devices in future sub 15 nm devices there is also an increasing interest in low energy implants. This suggests the role of surface degradation upon annealing will become even more important. Recent results along these lines are presented.
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