Effects of Al ion implantation to 4H-SiC on the specific contact resistance of TiAl-based contact materials

Abstract

To realize high-performance silicon carbide (SiC) power devices, low-resistance ohmic contacts to p-type SiC must be developed. To reduce the ohmic contact resistance, reduction of the barrier height at metal/SiC interfaces or increase in the doping concentration in the SiC substrates is needed. Since the reduction of barrier height is extremely difficult, the increase in the Al doping concentration in 4H-SiC by an ion-implantation technique was challenged. The Ti/Al and Ni/Ti/Al metals (where a slash ''/'' sign indicates the deposition sequence) were deposited on the Al ion-implanted SiC substrates. By comparing the experimental and theoretical contact resistances, the current transport mechanism through the metal/SiC interfaces was concluded to be thermionic field emission and the barrier height was determined to be $0.4 eV. Although the hole concentration increased with increasing the Al doping concentration in 4H-SiC, the barrier height at metal/SiC interfaces increased due to high density of dislocation loops observed in the implanted SiC layers by transmission electron microscopy. The present experiments suggested that the low-resistance ohmic contacts would be formed when a technique to eliminate the crystal defects formed in the 4H-SiC substrates after ion implantation was developed. r

The Impact of Process Conditions on Surge Current Capability of 1.2 kV SiC JBS and MPS Diodes

“…In this case, the P-ohmic contact contributes to device resistance, and the lower contact resistance helps to decrease the heat generation in surge events. According to previous experimental results [ 14 , 15 , 16 ], the P-ohmic contact resistance can range from 1 × 10 −3 Ω·cm 2 to 1 × 10 −5 Ω·cm 2 which is affected by the P+ implantation and ohmic contact annealing process conditions. In the simulation, the P-ohmic contact resistance was set as 1 × 10 −3 Ω·cm 2 , 5 × 10 −4 Ω·cm 2 , and 1 × 10 −4 Ω·cm 2 .…”

Nitriding of 4H-SiC by irradiation of fourth harmonics of Nd:YAG laser pulses in liquid nitrogen

“…For this reason, the expectation is focused on SiC as a next-generation power semiconductor. Because of a wide band gap of 3.26 eV, SiC-based power semiconductor devices can have advantages in the high voltage insulation strength and the robustness against high temperature [1][2][3]. In addition, SiC-based metal-oxide-semiconductor field-effect transistors (MOSFETs) have potential advantages in their low onresistance and high switching speed [4][5][6].…”

Optical ridge waveguides in 4H-SiC single crystal produced by combination of carbon ion irradiation and femtosecond laser ablation

“…As one of the most favorite third-generation semiconductors, silicon carbide (SiC) has attracted considerable attentions owing to its intriguing features, such as high thermal conductivity (~4.5 W/cm·K), high electric field breakdown strengths (~3 × 10 6 V/cm), and large band gap (~3 eV), for applications in high-power electronic devices of many fields, e.g., microelectronics, microwaves, aerospace, and nuclear reactor system to radar communication, etc [1][2][3][4][5]. The 4H-SiC, a member of SiC family, has a hexagonal structure and exists in a uniaxial crystal formed at the temperature above 1700°C.…”

“…The 4H-SiC, a member of SiC family, has a hexagonal structure and exists in a uniaxial crystal formed at the temperature above 1700°C. It has been widely used in the manufacturing of electronic devices which are of high frequency, enhanced power, and good radiation or interference resistance dependence [4]. The properties of 4H-SiC crystals on thermal conductivity [6], ferromagnetism [7], and Raman scattering [8] have been investigated by a few groups.…”