Electrically detected magnetic resonance of two-dimensional electron gasesin Si SiGe heterostructures

Strained Si/Si0.75Ge0.25 heterostructures, grown by solid source e-beam eva poration molecular-beam epitaxy on Si(100) substrates; have been studied by electrically detected magnetic resonance. Samples with a low-temperature m obility of about 10(5) cm(2)/V s were used, some with Schottky gates enabli ng control of the electron density in the channel. For T<50 K, a conduction -band electron-spin-resonance signal caused by electron-electron scattering in the two-dimensional channel was observed in the dark. The signal intens ity, g factor, and Linewidth were observed to depend on electron density n( e) and magnetic-held orientation. For n(e) = 4 x 10(11) cm(-2), g(parallel to) = 2.0007 (H parallel to the major conduction-band valley axis), and g(p erpendicular to) = 1.9999 (H perpendicular to major axis), which leads to a n anisotropy of g(parallel to)-g(perpendicular to) = (8 +/- 2) x 10(-4). Fo r n(e) < 3 x 10(11) cm(-2), the anisotropy nearly disappears. For H paralle l to[100],resonance linewidths as low as 70 mG are observed. A model for th e resonant change in the conductivity is developed and compared to experime nt. [S0163-1829(99)03420-7].