Electrical characterization was performed by using a combination of sourcemeter (Keithley 2612 A), Lock-In amplifier (Signal Recovery 7265) and resistance bridges (Lakeshore 370) coupled to a Physical Property Measurement System. The Raman spectra were measured in a backscattering geometry using a 488 nm laser excitation wave-length. Sub-Angström aberration corrected transmission electron microscopy was performed by using a JEM-ARM200cF microscope. EDS was performed through field- emission scanning electron microscopy (Zeiss 1540 XB).