Indentation response of two-dimensional materials mounted on different substrates

140For a small the elastic moduli ratio of 2D materials to their substrate (λ)(e.g., λ ≤ 100), the overall indentation response can be effectively described by the classic indentation model; whereas for a large λ (e.g., λ≥ 103), the indentation response begins to deviate from the behavior predicted by the classic indentation model.