Your one Stop Solution for Energy Level Characterisation Our most popular systems feature surface photovoltage (SPS) and photoemission spectroscopy capabilities to determine the absolute work function in ambient, controlled gas or vacuum environments. Knowledge of the electronic properties occurring in semiconductor materials is central to understanding light absorbing devices such as solar cells and light emitters such as LEDs. The relevant energy levels presented in the Energy Band diagram show the partially filled and unfilled electron energy bands against a vertical energy axis, with the zero energy, or Vacuum Level at the top. Semiconductors are characterised by two electron bands: the “Valence Band” (or in organic semiconductors the HOMO level) which is fully occupied by electrons up to energy E V and the upper “Conduction Band” (LUMO) which is partially populated from energy level E C. The semiconductor fermi-level E F is normally determined by the semiconductor bulk doping but can be influenced by illumination. Under dark conditions the vibrating Kelvin Probe (KP) provides the fermi-level E F, and with spectroscopic illumination (KP-SPS) energy E C can be determined. Ambient Pressure Photoemission spectroscopy (APS) provides E V.
