Abstract
Hydrogen-terminated silicon (Si) surfaces were characterized using an ultrahigh-vacuum (UHV) contactless capacitance–voltage (C–V) technique which has been recently developed by our group. In addition to a U-shaped background distribution, hydrogen termination proceeds a narrow discrete surface state peak at EV+0.65 eV whose density was sensitive to the treatment method and conditions. After optimal treatment in NH4F solution, a UHV-compatible completely passivated surface could be obtained with no appreciable discrete states. After annealing in an UHV environment above 300°C, the density of discrete surface states started to increase and eventually caused strong Fermi level pinning at EV+0.6 eV. The most likely origin of the discrete state is the Si dangling bond not terminated by hydrogen.