DOMAIN FORMATION IN MODULATION-DOPED GAAS AL(X)GA(1-X)AS HETEROSTRUCTURES/

We develop a theory of self-organized domain formation arising in char ge transport parallel to the layers of a modulation doped GaAs/Al(x)Ga 1-(x)As heterostructure in the regime of real space transfer from the high-mobility undoped GaAs layer into the low-mobility doped Al(x)Ga1- (x)As layer. We predict the existence of solitary travelling high-fiel d domains associated with packets of real space transferred electrons propagating parallel to the layers with velocities of the order of v a lmost-equal-to 2 x 10(5) m/s. This leads to transit time oscillations of f almost-equal-to 2 GHz for typical device dimensions of l = 100 mu m above fields of about 2 kV/cm. Chaotic domain motion can occur under a.c. drivijng conditions.