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

Abstract

The electrical conduction in an n-type In0.53Ga0.47As/InP sample grown by molecular 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 ascribed to the impurity band (IB), located in the interface between the epilayer InGaAs and the substrate InP. The contribution of the conduction band electrons in bulk InGaAs layer to the electrical conduction was negligible. The IB conduction was almost metallic. We observed within the IB two conducting channels which give positive and negative contribution to the Hall voltage. The magnetoresistance in the IB at low temperatures was negative, and at high temperatures was positive. The negative magnetoresistance in the IB has been phenomenologicaly described by carriers with the constant concentration and the mobility increasing proportionally to the square of the applied magnetic field.

Anomalous Behavior of the Hall Effect in III-V Heterostructures

“…1b we can see a small negative magnetoresistance in low magnetic field at temperatures below 59 K. Negative magnetoresistance has been widely observed in many semiconductors and magnetic materials [1,25,26].…”

“…In general, in the impurity band, the mobility of carriers is proportional to the concentration of structure defects producing impurity band states. From comparison of the mobility of impurity band carriers in m0.53 Ga0 4 7Αs/ΙnΡ (0.3 m 2 /(V s)) [1] and InAs/GaAs (0.8 m 2 /(V s)) heterostructures it can be concluded that the concentration of structure defects which form the impurity band is higher in the InAs/GaAs heterostructure. This is consistent with our assumption of a significant contribution of dislocations to the density of states in the impurity band in both heterostructures.…”

“…In such samples the contribution of the conduction band or valence band carriers to the conductivity can be small and effects associated with the interface can become dominant. In our previous paper we showed that in a thin, undoped In0.53Ga0.47As/ΙnΡ heterostructure nearly all the electrical conduction takes place in the impurity band at the interface [1]. The electrical conduction in the impurity band was about 95% of the total electrical conduction.…”

“…We assumed that quantum effects modify the electrical conduction of all three groups of carriers. In our model, the mixed electrical conduction was described using conductivity tensor components modified by quantum effects in the form where σi(B) = eniμi(B) is the sheet conduction, ni is the sheet concentration, μ i ( Β ) i s t h e m o b i l i t y [ 1 ] , e i s t h e e l e c t r i c c h a r g e , P s = μ 0 M s i s t h e m a g n e t i c polarization, MS is the saturation magnetization, assumed to be constant, μ0 is the permeability of free space, and μ S is the coefficient describing effect of the interaction of carriers with magnetic moment. In Eq.…”

“…Two groups of carriers have mobilities of about 0.8 m 2 /(V s) and another group of carriers has a mobility of about 0.1 m 2 /(V s). According to the analysis of the electrical conduction in the HgTe [33,34], GaN/AlGaN [35], and In0 53Ga0 4 7Αs/ΙnΡ [1] it is easy to show that the electrons in InAs at temperature below 100 K with the mobility about 0.8 m 2 /(V s) cannot be in the conduction band. Then, electron-like (n i ) and hole-like (p2) carriers with mobilities about 0.75 m2/(V s) were ascribed to the impurity band.…”