Measurement of nanohardness and nanoelasticity of thin gold films with scanning force microscope

With a scanning force microscope operating in ultrahigh vacuum, we measured local mechanical properties of single crystalline gold islands. The elastic moduli of the gold islands and the substrates sapphire, mica, and quartz were evaluated from force-distance curves. The value of Young's elastic modulus in [111] direction of the gold grains is (50 +/- 16) GPa and was found to be significantly smaller than the bulk modulus of gold. With an indentation technique, the nanohardness of gold islands was investigated. The nanohardness is smaller than the bulk value and depends on the indentation area. This can be interpreted as nanohardening by dislocation interaction in very pure single crystals. (C) 2000 American Institute of Physics. [S0003-6951(00)05429-2].