Observation of surface charge screening and Fermi level pinning on a synthetic, boronhyphen;doped diamond

摘要

Spectroscopic currenthyphen;voltage (Ihyphen;V) curves taken with a scanning tunneling microscope on a synthetic, boronhyphen;doped diamond single crystal indicate that the diamond, boiled in acid and baked to 500thinsp;deg;C in vacuum, does not exhibit ideal Schottky characteristics. TheseIhyphen;Vcurves taken in ultrahigh vacuum do not fit the traditional theory of thermionic emission; however, the deviation from ideal can be accounted for by charge screening at the diamond surface. At ambient pressure, theIhyphen;Vcurves have a sharp threshold voltage at 1.7 eV above the valence band edge indicating pinning of the Fermi energy. This measurement is in excellent agreement with the 1/3 band gap rule of Mead and Spitzer lsqb;Phys. Rev.134, A713 (1964)rsqb;.