Improving the doping efficiency of Al in 4H-SiC by co-doping group-IVB elements

TL;DR

This paper demonstrates that co-doping group-IVB elements, especially Ti, with aluminum in 4H-SiC significantly reduces ionization energy and enhances p-type doping efficiency, potentially enabling better semiconductor device performance.

Contribution

It introduces a co-doping strategy with group-IVB elements to effectively lower Al ionization energy in 4H-SiC, a novel approach to improve doping efficiency.

Findings

Ti co-doping reduces Al ionization energy by nearly 50%.

Ionization rate of Al with Ti co-doping is up to 5 times higher at room temperature.

The approach suggests a new pathway for enhancing p-type doping in 4H-SiC.

Abstract

The p-type doping efficiency of 4H silicon carbide (4H-SiC) is rather low due to the large ionization energies of p-type dopants. Such an issue impedes the exploration of the full advantage of 4H-SiC for semiconductor devices. In this letter, we show that co-doping group-IVB elements effectively decreases the ionization energy of the most widely used p-type dopant, i. e., aluminum (Al), through the Coulomb repulsion between the energy levels of group-IVB elements and that of Al in 4H-SiC. Among group-IVB elements Ti has the most prominent effectiveness. Ti decreases the ionization energy of Al by nearly 50%, leading to a value as low as ~ 0.13 eV. As a result, the ionization rate of Al with Ti co-doping is up to ~ 5 times larger than that without co-doping at room temperature when the doping concentration is up to 1018 cm-3. This work may encourage the experimental co-doping of group-IB elements such as Ti and Al to significantly improve the p-type doping efficiency of 4H-SiC.