Band diagram of diamond and diamond-like carbon surfaces

摘要

The electron affinity (EA) of various terminations of diamond surfaces has been calculated bythe ab-initio pseudopotential method. The bare, reconstructed (100) and (111) surfaces are found tohave positive EAs of 0.5 eV and 0.35 eV, respectively. The hydrogen-terminated surfaces 1× 1(100):2H, 2×1 (100):H and (111 ):H have sizeable negative EAs of orders -2.4eV, -2.0eV and - 2.0eV, respectively. Oxygen terminations give large postive EAs. The barrier height of adiamond/graphite Schottky barrie is found. These data are used to derive a band diagram for diamondand diamond-like carbon field emitters. The main barriei for electron emission from diamond is at theback contact, and nitrogen deep donors aid emission by creating a depletion layci that reduces thetunnelling distance. Diamond-like carbon has sizeable positive EAs. the main barrier is at the frontsurface, and nitrogen is a weak shallow donor that raises the Fermi level to lower the barrier.