Negative and positive magnetoresistance in GaInNAs/GaAs modulation-doped quantum well structures
- 247 Downloads
In this work, magnetoresistance of as-grown and annealed n- and p-type modulation-doped Ga0.68In0.32NyAs1−y/GaAs single quantum well structures with various nitrogen concentrations has been studied. At low temperatures and low magnetic fields, in n-type samples negative and in p-type samples positive, magnetoresistance has been observed. The observed negative magnetoresistance in n-type samples is an indication of enhanced backscattering of electrons due to the weak localization of the electrons as an effect of the N-induced defects. Nitrogen concentration and thermal annealing dependence of the magnetoresistance have been studied for both n- and p-type samples. The observed decrease in the negative magnetoresistance in n-type and enhanced positive magnetoresistance in p-type samples following thermal annealing have been explained by considering thermal annealing-induced improvement of mobility and the crystal quality in N-containing samples. After thermal annealing, the magnitude of negative magnetoresistance decreases and the breaking of the weak localization is achieved at lower magnetic fields in n-type samples. It is observed that as the mobility of the sample increases, critical magnetic field of negative to positive magnetoresistance transition becomes lower.
KeywordsThermal Annealing Hole Mobility Weak Localization Critical Magnetic Field Negative Magnetoresistance
This study was supported by The Scientific and Technological Research Council of Turkey (TUBITAK) Project Number 110T874, Scientific Research Projects Coordination Unit of Istanbul University Project Numbers 9571, 27643 and the Ministry of Development of Turkey Project Number 2010K121050. We are also grateful to Tampere University of Technology for growing samples and COST Action MP0805 for enabling collaboration with Tampere University of Technology.