Investigations Of Enhancing Biplor Resistance Effect And Lateral Photovoltatic Effect

As the important mechanism of precision sensor,the lateral photoelectric effect can be divided into lateral photovoltaic effect and bipolar resistance effect according to the different measuring methods.This study mainly introduced how to get the sensor with higher sensitivity,precision and stability.These three aspects as follows:1.We studied the enhanced bipolar resistance effect with the MWNTs-SiO₂-Si structure using the conducting layer of MWNTs.After comparative analysis to the spectral transmittance curves of MWNTs and the spectral reflectance curves of the MWNTs-SiO₂-Si structure,we found that the structure of the MWNTs-SiO₂-Si has a strong absorption rate to the laser with the wavelength of 532nm.The maximum resistance sensitivity of the bipolar resistance effect is 32.63 kΩ/mm.The symmetrical three-dimensional surface map of bipolar resistance effect on the condition of positive bias and negative bias were obtained by the experiments.And the sensitivity in electrodes connection direction and its vertical direction has been analysed.This thesis revealeded the mechanism of the bipolar resistance effect according to the effective electron density theory.The energy bands diagram of the MWNTs-SiO₂-Si structure is presented according to the model of the electron distribution in the equilibrium state,and the energy loss during the electron motion process has been analysed.2.We studied the enhanced lateral photovoltaic effect with the MWNTs-diatomite-SiO₂-Si structure by adding the polyporous diatomite which can lead to electron interference.The laser with the wavelength of 532nm was used as the illumination laser,and the voltage sensitivity with different laser power has been compared.The voltage sensitivity was117.04mV/mm when the laser power was 10mW.At the same time,the voltage sensitivity droped with the increase of the distance between electrodes.The voltage-position curve was nonlinear when the distance was 10mm.The mathematical models have been established using the insulator layer with holes.The electrons motion process has been analysed according to the electron interference theory.We put forward the enhancing mechnism of the lateral photovoltaic effect in the MWNTs-diatomite-SiO₂-Si structure,which provided a new direction to study enhanced lateral photovoltaic effect.3.We studied the enhanced lateral photovoltaic effect in the Si-Si_0.7Ge_0.3-Si and the MWNTs/Si-Si_0.7Ge_0.3-Si structure.The mormal Si semiconductor has been replaced by the Si-Si_0.7Ge_0.3-Si heterostrcture which has the narrow band gap.Comparing the Spectral reflection of the Si semiconductor and the Si-Si_0.7Ge_0.3-Si heterostructure,the Si-Si_0.7Ge_0.3-Si heterostructure has a stronger absorption to the visible light.Test results shows both the Si-Si_0.7Ge_0.3-Si heterostructure and the MWNTs/Si-Si_0.7Ge_0.3-Si structure have the nonlinear resistance-position relationship between two electrodes but have the larger resistance change ratio of 3489.31%and 4534.37%.By contrast,the voltage-position relationship curves of the Si-Si_0.7Ge_0.3-Si heterostructure and the MWNTs/Si-Si_0.7Ge_0.3-Si structure are according with the linear correlation of the lateral photovoltaic effect.The voltage sensitivity of the Si-Si_0.7Ge_0.3-Si heterostructure between two electrodes is 211.1mV/mm,and the voltage sensitivity of the MWNTs/Si-Si_0.7Ge_0.3-Si structure which added the MWNTs is288.4mV/mm.Both two sensitivities are higher than the 53.34mV/mm of the MWNTs-Diatomite-SiO₂-Si structure,which made the sensitivity of the lateral photovoltaic effect be further improved.The thesis is partially founded to reasearching the sensor with higher sensitivity.