**7. Conclusion**

*Nanostructures*

**110**

**Figure 11.**

*Fabricated GITS is tested for Ar at 10<sup>−</sup><sup>2</sup>*

**Figure 10.**

*(b) is reproduced from Abedini Sohi & Kahrizi [38]).*

*Room temperature I – V characteristics of He (a) and Ar (b) at a wide range of pressures (0.01–10 Torr) (part* 

*between the electrodes, the transition from complete breakdown to quasi breakdown is observed.*

 *Torr for different separation gaps. By increasing the separation gap* 

A novel fabrication technique, based on consecutive chemical and electrochemical etching techniques, is used to fabricate Si nanostructures. Si surface is textured by pyramidal hillocks through anisotropic etching in TMAH based solution. Electrochemical etching (anodic etching) of the textured Si was carried out in a HF-based solution in an electrochemical cell. Non-uniform distribution of the electric field induces different level of etching rate over the anode, which results in formation of the arrow shape structures. Mechanism of the developed structures is investigated by modeling and simulation by COMSOL multiphysics. Fabricated structures were applied as the anode in GITS. The total field enhancement coefficient (βtol) of the GITS is estimated based on the ohmic region of the gas discharge characteristics, as compared to a parallel-plates sensor. Field penetration and band bending at the surface of p-type nanostructures lead to tunneling current in the range of mA in low voltages and as a result, the fabricated Si nanostructure based GITS showed the capability to distinguish the unknown gases as well as the gas pressure.
