Photoelectric Effect Based-on Control Of Schottky Barrier Observed In Nano-structures Of Metal-oxide-semiconductor

Nano-structures of metal-semiconductor usually show more prominent photoelectric properties over traditional bulk materials,such as higher electrical conductivity,higher thermal conductivity and faster electron mobility,and so on.These excellent properties give nano-structures of metal-semiconductor broad applications in the field of high-tech such as aerospace,energy and information.Schottky contact is a very common contact in metal-semiconductor structures,and in conventional bulk Schottky contacts,the height of Schottky barrier is always fixed,only denpending on the work functions of metal and semiconductor,as well as the degree of Fermi level pinning effect.However,in nanoscale metal-semiconductor structures,the height of Schottky barrier may be influenced by some peculiar physical effects such as surface effect,tunneling effect,quantum size effect,etc,and then presents to be controllable.So people may design the structure of Schottky contacts in nanoscale to obtain different heights of Schottky barrier,which may bring more new applications,physical effects and the explorations of theoretical mechanism.This thesis is an exploratory research focusing on this subject.We designed nanoparticle films of different metals on semiconductor substrates,and found that the Schottky barrier of this structure can be changed by the stimulation of laser combined with electric pulse,reflecting on the measurable physical quantities,the photovoltage and resistance of this strutrue can be controllable under this stimulation.More interestingly,this regulation is non-volatile,i.e.when we removed the laser and electric pulses,the change of the barrier still exists.This feature may provide a promising application in the field of storage and control for this effect(laser assisted electric pulse controlling the height of Schottky barrier).We proposed a theory model based on the trap of light generated carriers in metal nanoparticle to explain this result,and later this model is verified in the measurement of lateral photovoltaic effect(LPE).According to the feature that Schottky barrier height of this structures are controllable,we designed a groove type merged Shottky junctions structure,and observed a diode effect with excellent reverse characteristics.Combined with the laser assisted electric pulse method,the reverse current can also be controllable in a nonvolatile manner.In addition,even if the material itself has no magnetism,this structure is very susceptive to magnetic field due to the asymmetry of carrier diffusion.Obvious magnetic tuning of LPE and light induced magnetoresistive effect are observed in this well designed structure,and we also proposed an explanation based on size magnetoresistive effect and the features of this structure.