Avalanche phenomena in 4H-SiC p-n diodes fabricated by aluminum orboron implantation

Characteristics of p-n junction fabricated by aluminum-ion (Al⁺) or boron-ion (B⁺) implantation and high-dose Al⁺-implantation into 4H-SiC (0001) have been investigated. By the combination of high-dose (4×10¹⁵ cm^-2) Al⁺ implantation at 500°C and subsequent annealing at 1700°C, a minimum sheet resistance of 3.6 kΩ/□ (p-type) has been obtained. Three types of diodes with planar structure were fabricated by employing Al+ or B+ implantation. B ⁺-implanted diodes have shown higher breakdown voltages than Al⁺-implanted diodes. A SiC p-n diode fabricated by deep B+ implantation has exhibited a high breakdown voltage of 2900 V with a low on-resistance of 8.0 mΩcm² at room temperature. The diodes fabricated in this study showed positive temperature coefficients of breakdown voltage, meaning avalanche breakdown. The avalanche breakdown is discussed with observation of luminescence