WELL DEPTH FLUCTUATION OF SI1-XGEX SI QUANTUM-WELL STRUCTURES STUDIEDBY CONDUCTANCE-VOLTAGE TECHNIQUE/

A conductance method is proposed to study the interfacial band offset and the well depth fluctuation of SiGe/Si quantum well structures. Bas ed on an equivalent circuit model, the frequency-dependent and tempera ture-dependent conductance-voltage (G-V) characteristics of quantum we ll structures are analyzed. It is revealed that corresponding to each well a conductance peak will appear in the G-V curve and meanwhile a c apacitance step will appear in the capacitance-voltage curve. By this conductance method the position of the Fermi level as functions of app lied bias voltage and temperature can be obtained in a wide voltage ra nge. The conductance method is found to be an effective method to meas ure not only the band offset of single quantum well but also the well depth fluctuation of multiple quantum wells. (C) 1998 American Institu te of Physics. [S0021-8979(98)04722-7].