Silver Nanoparticle Enhanced Photoelectric Effect Of Bi₂Te₃/Si Heterojunction

Photoelectric effect refers to the phenomenon that the electrical properties of materials change under light irradiation.According to different lighting and working modes,it can be divided into longitudinal photoelectric effect and lateral photovoltaic effect.Bi₂Te₃ as a kind of wide-band photoelectric detection ideal material,with a band gap is narrow,characteristics of light absorption coefficient,scientists have been one of the top materials in research on the photoelectric device,but the research is still relatively lack,especially its lateral photovoltaic effect and the light position sensitive detector research and rarely reported.Based on Bi₂Te₃/Si heterogeneous became the object of study,the system studied the longitudinal and lateral photovoltaic effect photoelectric effect,and with the introduction of Ag nanoparticles enhanced surface plasmon resonance to improve its photoelectric detection performance and lateral photovoltaic response characteristics,for the application of the heterojunction in multi-function optoelectronic devices and research to lay a solid foundation.First of all,Bi₂Te₃ films were prepared on n-type Si substrate by magnetron sputtering coating system.By changing the sputtering time,5 samples with Bi₂Te₃ film thickness of 10.5nm,14 nm,28 nm,42 nm and 56 nm were obtained,the samples by SEM,XRD,Raman,absorption and transmission spectra test,studied the Bi₂Te₃ thin film thickness and laser power changes affect the performance of photoelectric detection.Through the calculation of optical responsivity and detection degree,it is found that the sample's responsivity and detection degree decrease with the increase of laser power,but it is strongly dependent on the thickness of the film.The sample of 14 nm has the highest responsivity and detection degree,with the responsivity reaching 0.135 A/W and the detection degree reaching 0.4×10¹00 Jones.The influence of Bi₂Te₃ film thickness on the lateral photovoltaic response of Bi₂Te₃/Si junction was also studied.The position sensitivity of different samples increased exponentially with the increase of laser power,and gradually became saturated.The 10.5nm sample had the highest sensitivity,reaching 135 mV/mm,and the nonlinear degree remained within 10%.Secondly,on the basis of the original structure,a layer of Ag nano-film was introduced into the interface of Bi₂Te₃/Si heterojunction through the magnetron sputtering coating system to form the Bi₂Te₃/Ag/Si structure.By changing the sputtering time,Ag nano-films of different thickness were prepared,which were 2.2 nm,4.4 nm,6.6 nm and 8.8 nm respectively.The morphology of the Ag nano-film was observed by SEM.The Ag nanometer film was discontinuous and composed of discrete Ag nanoparticles.After the introduction of Ag nanoparticles,the interaction between the incident light and the Ag nanoparticles generated local plasma resonance,which enhanced the absorption of light.Finally,the effects of the thickness of Ag nano-film and the laser power on the photoelectric detection performance were studied.The responsivity and detectivity of the samples with different thickness of Ag nano-film are still decreasing with the increase of laser power,but there is no Ag nanoparticles relative to sample,to improve the performance of different level,the light response of the Ag nano-film samples of 6.6 nm and detect the highest degree,responsivity of 0.128 A/W,than under the same conditions did not introduce the sample of the Ag nanoparticles?0.075 A/W?increased nearly 1.7 times;The detection degree reached 0.47×10¹00 Jones,which was nearly 5.9 times higher than that of samples without Ag nanoparticles?0.08×10¹00 Jones?under the same conditions.The effect of Ag nano-film thickness on the lateral photovoltaic effect of Bi₂Te₃/Si structure were slso studied,and find that the introduction of silver nanoparticles can also improve the lateral photovoltaic response performance.In particular,the position sensitivity of the sample of Ag nano-film at6.6 nm reaches the maximum of 168 mV/mm,which is nearly 2.7 times higher than that of the sample?62 mV/mm?without Ag nanoparticles under the same conditions,and the nonlinearity was also reduced?between 2%and 6%?.