Synthesis of SiNWs Array by Metal-Assisted Chemical Etching

According to special feature of Silicon nanostructures, they have also used in some new devices such as sensors[1], solar cells[2] and lithium-ion batteries. Among the silicon nanostructure silicon nanowires have been identified as one of well-known nanostructures in the semiconductors application [3]. Also, among the methods that used to synthesis of SiNWs, the MACH has beenapplied because of low cost, controllability and fast synthesis.MethodsThe silicon wafer (p-type, 8-12 Ω.cm and <111> direction) was cut to 1*1 cm2 square and washed with H2SO4:H2O2 in ratio of 3:1 (v: v) for 10 minutes. Then it was immersed into solution of 5% HF for 3. The samples were placed into these solutions mixture of AgNO3=0.005 M and HF=4.8 Mfor one minute. In last step, the sample was placed in solution mixture of H2O2=0.8 M and HF=4.8 M. in order to remove silver particles the sample was placed in solution of HNO3:H2O2 by ratio of (1:1, v: v) and washed with deionized water and dried by N2. The sample was characterized by FESEM(MIRA3 TESCAN) equipped with EDX.Result and discussionThe figure 1-a shows the FE-SEM cross section of SiNWs array. As shown in figure 1-a, the silicon nanowires have been synthesized by the length of 8.5 μm. Also the figure 1-b shows the SiNWs has been formed by diameter of 40 nm. On the other hand, holes were completely injected beneath of silver particles and the silver particles are sunk and localized etching has happened. The uniform silver particles layer is necessary to form the SiNWs array. On the other hand, in the second step the silver particles play catalysis role and help to transfer of holes to silicon valance band.ConclusionIn summary, we have successfully synthesized of SiNWs array by MACE. Also, the holes injection plays the most important role in MACE. Therefor the SiNWs whit diameter of 30nm was formed.As a result, the uniform of silver particles layer is necessary to form the SiNWs array.

کلیدواژه ها:

SiNWs array ، Metal assisted chemical etch ، Electroless reactions ، Silver plating