Revealing the Dopant Incorporation Mechanisms into Vapor-Liquid-Solid Grown NWs Employing Nano-Prope Scanning Auger Microscopy

Nanowires (NWs) have been extensively studied over the last few decades for both scientific interest and technological potential. Semiconductor NWs’ physical properties are profoundly dependent on their chemical composition and especially so on their dopant concentration, profiles and activity level. Controlling NWs axial and radial dopant profiles is, therefore, of utmost importance for NW-based device optimization. Over the last few years various works have shown inhomogeneous dopants profiles in many NWs systems, yet further improvement in the challenging chemical characterization of individual NW is therefore required for the identification and understanding of doping mechanisms. Recent instrumentation advances in nano-probe Field Emission Scanning Auger (npSAM), combined with low voltage sputter ion depth profiling, allows the analysis of the axial and radial elemental distributions of individual NWs. This study employed npSAM to extract the axial and radial dopant distributions of P doped SiNWs grown under various conditions and provided new insights into some of the key questions regarding the dopant incorporation mechanisms. The comparison between both axial and radial dopant profiles of SiNWs grown under different conditions assisted to quantify and distinguish between the two different dopant incorporation mechanisms (catalytic vs. side wall deposition), revealed the radially inhomogeneous catalytic doping and the self-enhancing nature of the side wall dopant incorporation, and demonstrated a surprisingly substantial reservoir effect.