Contactless characterization of surface and interface band-bending in Silicon-On-Insulator (SOI) structures

The Kelvin-probe method is capable of determining electrical properties of the near-surface region of the SOI material as well as the BOX–substrate interface without any device preparation process and completely in a nondestructive manner. It is shown that a simple sandwich-type electrode configuration can be used for the contactless characterization of the SOI layer, when the capacitance between the vibrating electrode and the SOI surface is much smaller than the buried-oxide (BOX) and depletion-layer series capacitances. With the use of ultraviolet (UV) light source for the surface-photovoltage (SPV) measurement, the surface band-bending of very thin SOI layers can be characterized, while infrared (IR)-illumination is capable of searching deeper region.