Electron spin resonance on a two-dimensional electron gas

Electron-spin-resonance (ESR) data obtained from modulation-doped ${\mathrm{S}\mathrm{i}/\mathrm{S}\mathrm{i}}_{1-y}{\mathrm{C}}_y$ heterostructures are reported. The observed signals show that the small number of electron spins in these two-dimensional structures is still sufficient to detect ESR directly, and we have strong indications that the prominent line in the spectra is due to conduction electrons confined in the ${\mathrm{Si}}_{1-y}{\mathrm{C}}_y$ layers, forming a two-dimensional electron gas. We compare our results to the case of confined electrons in III-V heterostructures and quantum wells, where only indirectly detected ESR experiments have been reported so far.