FREQUENCY-RESOLVED ADMITTANCE MEASUREMENTS ON INAIAS INGAAS/INAIAS SINGLE-QUANTUM WELLS TO DETERMINE THE CONDUCTION-BAND OFFSET AND THE CAPTURE COEFFICIENT/

Frequency-resolved admittance measurements have been used to determine the conduction band offset and the capture time constant of In0.52Al0 .48As/InxGa1-xAs/In0.52Al0.48As single-quantum well (SQW) structures. A theoretical analysis of the SQW admittance taking into account nonpa rabolicity of the conduction band is reported. Analytical expressions for both capacitance and conductance as a function of both bias and fr equency have been deduced and used to fit the experimental data. As a result the conduction band offset and the capture time constant have b een obtained. Two different well compositions, x = 0.53 lattice-matche d and x = 0.60 strained, have been studied. In both cases the well wid th was 5 nm. The obtained conduction band offset at room temperature i s DELTAE(c) = 0.47 +/- 0.03 eV for x = 0.53 and DELTAE(c) = 0.52 +/- 0 .04 eV for x = 0.6. The capture coefficient of the carriers in the fir st subband in the well is in the range 3 x 10(-7) to 7 x 10(-7) cm3/S for x = 0.53 and in the range 3 x 10(-7) to 13 x 10(-7) cm3/S for x = 0.6.