OBSERVATION OF EXCITONIC FEATURES IN ZNSE ZNMGSSE MULTIPLE-QUANTUM WELLS BY NORMALIZED KELVIN PROBE SPECTROSCOPY AT LOW-TEMPERATURES/

The surface photovoltage spectra (SPS) of a series of ZnSe/ZnMgSSe mul tiple quantum wells of different well thickness (15-120 Angstrom) have been obtained as a function of temperature (48 K < T < 300 K) using a contactless Kelvin probe. In contrast to previous SPS measurements ou r data were taken using normalized incident light intensity. This norm alization procedure has made it possible to fit the numerical derivati ve of the spectra (with respect to photon energy) to an appropriate li neshape factor to accurately determine the energies of the excitonic t ransitions. From the splitting between the fundamental conduction to h eavy (11H)- and light (11L)-hole transitions as a function of well wid th we have confirmed the conduction band offset deduced by K. Shahzad et al. [Appl. Phys. Lett., 67, 659 (1995)]. We also have observed an i nteresting temperature dependence of the intensities of the 11H and 11 L SPS features for different well widths. (C) 1997 Published by Elsevi er Science Ltd.