1 Supporting Information Discovery of High-Temperature Superconductivity (T c = 55 K) in B-Doped Q-Carbon Anagh Bhaumik 1† , Ritesh Sachan 1,2† , Siddharth Gupta 1 , Jagdish Narayan 1* 1 Department of Materials Science and Engineering, Centennial Campus North Carolina State University, Raleigh, NC 27695-7907, USA 2 Materials Science Division, Army Research Office, Research Triangle Park, NC 27709, USA *Correspondence to: narayan@ncsu.edu † Authors have equal contribution in the manuscript ADDITIONAL INFORMATION TOF-SIMS measurements and correlations: Figure S1(A) indicates the TOF-SIMS profile of the superconducting B-doped Q-carbon sample (T c =55 K). An effective laser-material coupling is achieved using the C as the top layer in the B-C layered composite structure. This leads to laser-induced melting and subsequent rapid quenching process thereby leading to the formation of highly B-doped Q-carbon structure. The periodic variation of SIMS spectral intensity of B and C is flattened out after the PLA process (shown in Figure S1(A)). This indicates a complete melting (of C and B) followed by liquid phase diffusivity. From dopant profile broadening, the diffusivity coefficient was derived to be ~ 2×10 -4 cm 2 /sec. A Boron enriched layer (~45 at% B) is formed at the interface (between metallic B and 27 at% B-doped Q-carbon) and is shown in Figure S1(B). The atomistic details of this highly-doped layer are discussed in the EELS section. The uniformity of B/C concentration profile in the B-doped Q- carbon thin film is an important criterion for high-temperature superconductivity (and is also