少子寿命和表面形貌与多孔硅发光性能的关系

研究了不同时间腐蚀的多孔硅的光致发光性能与多孔硅的表面形貌和少子寿命之间的关系。结果表明,多孔硅的发光来自与氧空位有关的缺陷,而多孔硅表面的氢原子能够钝化多孔硅表面的非辐射中心从而提高多孔硅的发光效率。多孔硅的空隙度随腐蚀时间的延长而增大,这也导致了多孔硅的少子寿命的降低,从而造成多孔硅的光致发光效率随多孔硅空隙度的增大以及少子寿命的降低而提高。另外,原子力显微照片表明长时间的腐蚀使多孔硅表面层被化学腐蚀,从而降低了多孔硅表面的粗糙度。

Relationship between Minority Carrier Life and Morphology with Luminescent Properties in Porous Silicon

The relationship between minority carrier life and morphology with luminescent properties in porous silicon was studied.The surface morphology of the porous silicon(PS)samples was observed by the field emission scanning electron microscopy(FESEM)and the atom force microscopy(AFM)and microwave photo-conductance decay(μ-PCD)technique was first used to measure the minority carrier lifetime of PS.The results show that the porosity of porous silicon increased with the increase of etched time,which lead to the decrease of minority carrier life and the increase of luminescent efficiency of porous silicon.When the minority carrier life of PS decreases,the irradiative centers on surface of PS increase,which lead to decreasing of photoluminescence(PL)efficiency.Furthermore the results of μ-PCD technique showed the un-uniformity of minority carrier life of PS,which lead to the un-uniformity of PL efficiencies on different location of PS surface.This result proved that the formation of PS is depending on current density and back illumination strength.The results of the PL spectra and the Fourier transform infrared(FTIR)spectra illuminated that the emission came from the formation of surface confined emitters that related to the defects in silicon dioxides and the hydrogen atoms on surface of PS samples played as a key role to dissipate the irradiative centers and increase the PL efficiency.In addition,the result of morphology observation by atomic force microscopy exhibited that the surface of porous silicon became smooth gradually with increase of etched time,which may be related to the chemical etching during the electrochemical etching process.