The Magnetoresistance Effect Of Semiconductor Pn Junction

According to the prediction of Moore's law,semiconductor electronics is now reaching its fundamental limits,which means that the performance of traditional semiconductor is hardly promoted.So,to realize the large magnetoresistance effect of semiconductor gives not only the traditional semiconductor new application value,also can give new research approach to magnetoelectronics.So far,various semiconductor materials from narrow gap semiconductors such as Ag2Te/Se,InSb and WTe2 to conventional and commercialized semiconductors such as GaAs,Ge and Si all have shown that the electric transport behavior can be significantly modulated by the magnetic field,which yields an unexpectedly large and unsaturated magnetoresistance.However,as a core component of the semiconductor device,the research of pn junction magnetoresistance effect is still lacking,which will not avail the further development and application of semiconductor magnetoelectronics devices.Therefore,we chose the traditional semiconductor silicon and gallium arsenide as the material to fabricate the pn junction diode and Schottky diode by using photolithography,ion implantation and magnetron sputtering techniques.And we have studied the magnetoresistance effect of pn junctions from both theory and experiment.The innovative results are as follows:1.Starting from the transport equation of the traditional single pn junction,we found the configuration of pn junction space charge region will be modulated by external magnetic field and the transport behavior of pn junction will change a lot.According to the calculation,when a three Tesla magnetic field is applied,the pn junction magnetoresistance can reach 20% at the room temperature,which indicates that the traditional pn junction diode is expected to become a multifunctional device which couples the electric field and magnetic field.And our consideration has been confirmed by the experiment.2.We fabricated the magneto-photogalvanic device of period pn junction dot arrays in the GaAs substrate by ion implantation.With an increase in magnetic field from 0 to 1500 Oe,the photovoltage increases linearly for a wide temperature range from 80 to 430 K.Compared with GaAs without the dot arrays,periodic GaAs dot arrays have a hundredfold increase of the magnetic-field-modulated photovoltage at room temperature,which can reach 74?V/Oe.By changing the temperature and dot spacing,we consider that the enhancement of magneto-photogalvanic effect is attributed to the pn junction coupling.3.We fabricated Si/Ni80Fe20 Schottky diode by magnetron sputtering technique and studied its anisotropic magneto-seebeck effect(AMS).A thermoelectric potential between adjacent electrodes is produced by laser heating the sample.When the magnetic moment of Ni80Fe20 rotates from perpendicular to the temperature gradient to parallel to the temperature gradient,the thermoelectric potential has a change of 1.2 ?V.And we calculated the AMS value is 0.606%,which is similar to the AMR ratio(0.541%).Therefore,we consider AMS and AMR effect stem from the same physical mechanism.