Low loss, large area 4.5 kV 4H-SiC PIN diodes with reduced forward voltage drift

We report nitrogen (N) doping of 4H-SiC by KrF excimer laser irradiation in liquid N2. In comparison to phosphorus (P) doping performed using phosphoric acid solution, the laser N doping can introduce N atoms deeper (∼1 µm depth) into the 4H-SiC, which results in reduction of doped layer resistance by approximately 3 orders of magnitude. Doping is shown to proceed by the thermal diffusion of species, while loss of the host material from the surface by ablation takes place at the same time. Chemical analysis shows that high density carbon (C) vacancies are generated in the N doped region, which suggests enhanced diffusion of N assisted by the presence of C vacancies. pn junction diodes are formed by using the N doping technique. Turn-on voltage is ∼−3 V, which is reasonable for a pn junction diode of 4H-SiC.

Section: Introductionmentioning

confidence: 99%

Nitrogen doping of 4H-SiC by KrF excimer laser irradiation in liquid nitrogen

Ikeda¹,

Marui²,

Ikenoue³

et al. 2015

“…Therefore, the loss of 4H-SiC devices is several hundred times lower than that of Si devices for a given breakdown voltage. [5][6][7] However, there are issues in the process technology for producing SiC devices. One of the issues in SiC device fabrication is local doping.…”

Section: Introductionmentioning

confidence: 99%

Aluminum doping of 4H-SiC by irradiation of excimer laser in aluminum chloride solution

Marui

Ikeda

Nishi

et al. 2014

We have found that aluminum doping into 4H-SiC is performed by irradiating excimer laser light to 4H-SiC immersed in aluminum chloride solution. Aluminum is introduced in SiC at the concentration of over 1 × 1020 cm−3 near the surface while, chlorine hardly diffuses into 4H-SiC. After the laser irradiation in aluminum chloride solution, the resistance of the laser-irradiated region decreases with increasing laser fluence. Hall effect measurement shows that the laser irradiation produces a p-type layer and that its sheet carrier concentration is 2.14 × 1011 cm−2. In addition, we produce a pn junction by doping the surface of n-type 4H-SiC and by aluminum doping. The pn junction shows rectifying characteristics whose on/off ratio is about 7 decades and ideality factor is 1.15. This technique is one of the strong candidate local doping techniques for SiC.

“…Therefore, the contact resistance value can be obtained using Eqs. ( 1), (2), and (3) by changing the contact area "d × d" between the electrode and semiconductor. The graphs show the typical contact resistance measurements.…”

Section: Contact Resistance Measurement Methodsmentioning

confidence: 99%

“…It has superior material properties; particularly, 4H-SiC has a high dielectric breakdown field, which is approximately 10 times larger than that of silicon (Si). [1][2][3][4][5] Currently, Schottky barrier diodes and metal-oxide-semiconductor field-effect transistors are being commercialized and widely used. [6][7][8] However, there are several issues in the processing technology for 4H-SiC devices; one is the doping process.…”

Section: Introductionmentioning

confidence: 99%

Laser doping mechanism of 4H-SiC by KrF excimer laser irradiation using SiNx thin films

Yasunami

Nakamura

Katayama

et al. 2023

In this study, nitrogen is doped into 4H-SiC by irradiating 4H-SiC with a SiNx thin film and a KrF excimer laser. The doping depth profile, crystal structure, electrical properties, and surface roughness results are used to evaluate the excimer-laser doping mechanism. High concentration doping was possible at a fluence of 2.5 J/cm² and 10 shots while maintaining the 4H-SiC crystal structure by solid-phase diffusion. However, damage to the 4H-SiC structure was observed by liquid-phase diffusion at a fluence of 2.8 J/cm² or higher. At a fluence of 2.5 J/cm² and 100 shots, nitrogen could be deeply diffused by solid-phase diffusion, but an amorphous layer was formed on the surface and there was an increase in contact resistance.