The Ambient-pressure Photoemission Spectroscopy (APS) systems are one of KP Technology Ltd’s most recent additions to our large surface analysis range. Domestic and international patents are held for these instruments. APS measures the absolute work function (Φ) of a material by photoemission in ambient conditions, no vacuum is required. The excitation range of APS is 3.4 eV to over 7.0 eV, meaning that APS is capable of measuring the absolute work function of metals and the ionization potential of semiconductors alongside measurement of the surface Fermi level with the Kelvin probe.

If an SPV and SPS source is added to the APS system, the full bands of semiconductors can be measured in one complete desktop system; no other product in the world can do this.

When light is incident on a material such as a metal or a semiconductor, the photons may have enough energy to liberate electrons from the surface, a process known as the Photoelectric Effect.

The energy required for electrons to escape the material is termed the work function. By varying the energy of the incoming light, the absolute work function can be established.

Based on Fowler’s analysis of photoemission, the square root (cube root for semiconductors) of the photoelectron yield is plotted on a graph versus the incident photon energy (image right). The work function of the material under analysis is where this straight line extrapolates to zero.