Controllable growth of P-type graphene on the boron ion-implanted Si-face of SiC (0001)

Abstract

Realizing the reliable modulation of the carrier type and density in graphene is a challenging task, especially for epitaxial graphene (EG) grown in situ on SiC via thermal decomposition. In this process, doping is seldom adopted for substrate pretreatment, and the residual carriers in EG are determined by the properties of the SiC substrate and the random defects in EG. Here, we demonstrate a simple and effective technique for hole doping in EG on the Si-face of SiC (0001) implanted with boron ions. P-type EG with a carrier concentration of approximately 1–2 × 1012 cm−2 and a room-temperature mobility of 100–300 cm2/V s was achieved at the boron ion dose of approximately 1 × 1015 cm−2 at a centroid depth of approximately 140 nm from the SiC surface. These transport properties are comparable with the data reported for unintentionally doped P-type EG on the Si-face of SiC [Tedesco et al., Appl. Phys. Lett. 95, 122102 (2009)], for which the Hall device size was 40 times smaller compared to our device. The formation of P-type EG on the Si-face of SiC (0001) in this study was attributed to the synergetic effects of boron doping in EG and the transfer of electrons from EG into SiC. The detailed mechanisms are studied and discussed in this paper. The method demonstrated herein can be universally applied to downshift the Fermi level of EG on SiC, regardless of the crystallization orientation or polytype. The developed method is also compatible with modern semiconductor procedures.