Paper AS-MoM11
Chemically Resolved Electrical Characterisation of Working Devices by XPS

Monday, October 29, 2012, 11:40 am, Room 20

A noncontact chemical and electrical measurement technique of XPS is performed to investigate a CdS based Photoresistor and a Si-Diode during their operation. The main aim of the technique is to trace chemical and location specified surface potential variations as shifts of the XPS peak positions under operating conditions. For the Photoresistor Cd3d and for the Diode (p-n junction) Si2p peaks positions have been recorded, respectively. The variations in the Cd3d peak without and under photoillumination with 4 different lasers is extracted to yield the location dependent resistance values, which are represented; (i) two dimensionally for line scans, and (ii) three dimensionally for area measurements. In both cases one of the dimensions is the binding energy. For the Si p-n junction the variations in the Si2p peak position under normal and reverse bias are recorded to differentiate and identify the nature of the doping (p- or n-). The main advantage of the technique is its ability to assess element-specific surface electrical potentials of devices under operation based on the energy deviation of core level peaks in surface domains/structures. Detection of the variations in electrical potentials and especially their responses to the energy of the illuminating source in operando, is also shown to be capable of detecting, locating, and identifying the chemical nature of structural and other types of defects.