OPTOELECTRONIC MEASUREMENT OF SEMICONDUCTOR SURFACES AND INTERFACES WITH FEMTOSECOND OPTICS

The basic concepts and preliminary applications of optically induced electromagnetic radiation from semiconductor surfaces and interfaces by using femtosecond optics are discussed. This submillimeter-wave radiation provides a novel optoelectronic technique to study semiconductor electronic surface and interface properties with a contactless approach. The amplitude and phase of the electromagnetic radiation from the semiconductor surfaces depend on carrier mobility, impurity doping concentration, and strength and polarity of the static internal field. A large selection of bulk, epitaxial layer and superlattice samples from III-V, II-VI and group-IV semiconductors has been tested. The orientation and strength of the static built-in fields of a wide range of semiconductor surfaces, such as surface depletion, metal/semiconductor Schottky, p-n junction and strain-induced piezoelectric fields, can be determined and estimated.