Carrier profiling in Si-implanted gallium nitride by Scanning Capacitance Microscopy

To face silicon limits, gallium nitride (GaN) exhibits major interests for optoelectronics and power electronic devices. Nevertheless, several challenges have to be overcome, with local doping by ion implantation as a major one. It requires development of reliable characterization tools able to provide electrical information with nanoscale resolution. In this work, Atomic Force Microscopy (AFM) combined to its Scanning Capacitance Microscopy (SCM) mode was used for surface damages quantification and nanoscale dopant profiling. GaN samples have been implanted with Si in order to obtain a box-like profile and annealed above 1000 °C under nitrogen with AlN protective cap layer. SCM measurements have led to reliable and quantitative dopant electrical activity measurements thank to calibration sample. Moreover, a good agreement, in terms of depth and shape, has been obtained between SCM and SIMS profiles. This work has evidenced that a high activation rate of implanted Si can be achieved using rapid thermal annealing.