Negative magnetoresistance and impurity band conduction in an In0.53Ga0.47As/InP heterostructure

The electrical conduction in an n-type In0.53Ga0.47As/InP sample grown by m olecular beam epitaxy has been analyzed in the magnetic field up to 1.5 T, at temperatures from 15 to 295 K. The electrical conduction has been ascrib ed to the impurity band (IB), located in the interface between the epilayer InGaAs and the substrate InP. The contribution of the conduction band elec trons in bulk InGaAs layer to the electrical conduction was negligible. The IB conduction was almost metallic. We observed within the IB two conductin g channels which give positive and negative contribution to the Hall voltag e. The magnetoresistance in the IB at low temperatures was negative, and at high temperatures was positive. The negative magnetoresistance in the IB h as been phenomenologicaly described by carriers with the constant concentra tion and the mobility increasing proportionally to the square of the applie d magnetic field. (C) 1999 American Institute of Physics. [S0021-8979(99)04 809-4].