Work function measurements for surface analysis

A measurement system for measuring a sample, the measurement system comprising:

• an excitation system comprising a plurality of excitation sources generating excitations of different types comprising:
• a high energy radiation source generating high energy electromagnetic radiation;
• at least one electric power supply providing a bias voltage to a sample;
• and at least one electron beam source generating low-energy e-radiation in the form of an electron beam;
• said excitation system being configured and operable to perform at least one measurement session on at least a region of the sample comprising first and second sequentially performed measurement modes, the first measurement mode comprising exciting said at least region of the sample by the high energy radiation to induce a first-mode secondary electron emission spectral response of said at least a region of the sample, and the second measurement mode comprising supplying initial bias voltage to the sample and exciting said at least region of the sample by the e-radiation of the relatively low energy electron flux followed by a gradual variation of the bias voltage from said initial bias voltage to induce a second-mode electric current variations in the sample;
• a detection system comprising a spectrometer configured and operable to detect said first-mode secondary electron emission spectral response of the at least region of the sample to the high energy radiation excitation and generate corresponding first-mode measured data, and comprising an ammeter for monitoring the electric current through the sample and generating second-mode measured data indicative of sample current readout;
• and
• a control unit configured for signal communication with the detection system for processing the first-mode measured data and the second-mode measured data, said processing comprising identifying, in the first-mode measured data, a low kinetic energy onset of the secondary electron emission spectral response being indicative of a first measure of a work function of the sample, identifying in the second-mode measured data a turning point in the sample current readout corresponding to an effect of electrons being landing on a surface of the sample and being indicative of a second measure of a work function of the sample, and analyzing the first measure and the second measure of the work function and determining an effective work function of the sample.