Weak-fieldgfactor of the two-dimensional electron gas at the (In,Ga)As/InP interface

We have measured the weak-magnetic-field electron g factor of the two-dimensional electron gas found in a modulation-doped heterojunction formed from (In,Ga)As and InP. The g factor was determined by observing the spin-splitting zeros in the Shubnikov--de Haas oscillations as a function of total magnetic field in the temperature interval from 2 to 10 K. Extrapolating to zero field gives {}g*{}=4.5±{}0.25, independent of temperature in the low-temperature limit. Estimates of the band-edge g factor in bulk (In,Ga)As lead to an estimate of 0.5 for the exchange enhancement of the g factor of this two-dimensional electron gas.