Fabrication of Lanthanum Oxide Nanostructures using Extremely Non- Equilibrium Plasma and their Characterization Onkar Mangla and M. P. Srivastava Onkar Mangla and M. P. Srivastava Department of Physics and Astrophysics, University of Delhi, Delhi , INDIA Abstract: Lanthanum oxide (La 2 O 3 ) is a promising material for CMOS gate applications due to its high dielectric constant close to 30 and large band gap equal to 4.3 eV. In the present work, extremely non-equilibrium, high temperature and high density argon plasma produced in a modified dense plasma focus (DPF) device is used for producing ions from the pellet of La 2 O 3 placed on top of the anode in DPF device. These ions along with argon ions move vertically upward in a fountain like structure and material ions get deposited on the silicon substrates placed at 4.0 cm above top of the anode. This process of production of material ions from the La 2 O 3 pellet for deposition on silicon substrates for obtaining nucleation and nanostructures has been done using one, two and three focused DPF plasma shots. The structural properties of deposited material are studied using X-ray diffraction (XRD). The measurement of current-voltage characteristics is done to study the electrical properties of deposited material. Introduction In the present time a lot of research effort is devoted to search for new alternative dielectric materials for CMOS technology. As the dimensions of MOSFET devices are scaled down, materials having higher dielectric constant should replace SiO 2 gate dielectric: high-k materials. Lanthanum oxide, La 2 O 3, could be considered as a candidate for CMOS gate application, since it has high dielectric constant ~ 30 and large band gap ~ 4.3 eV. Moreover, La 2 O 3 has shown to be compatible with current semiconductor manufacturing processes, a critical factor from both the technological and economical viewpoints. However, in most of the previous research papers [1-3] the fabrication of La 2 O 3 thin film is there. In this paper we have fabricated La 2 O 3 nanostructures on silicon substrates using the ions of material generated by extremely hot, dense and non-equilibrium argon plasma in a modified dense plasma focus (DPF) device. The as- deposited material is structurally characterized by X-ray diffraction (XRD) and electrical properties are studied using current-voltage (I-V) characteristics. Experimental The DPF device is a 3.3 KJ Mather Type [4]. Top of the anode is modified using a detachable arrangement such that it can hold the material pellet on top. Powdered La 2 O 3 is compressed at a pressure of 10 MPa in a pellet making machine and then the pellets are sintered at 700°C for 3h in a furnace. The pellet is fitted on the top of the modified anode. Plasma chamber of DPF is filled with argon gas and then evacuated to maintain a pressure of 80 Pa. We charge the capacitor to 15 kV and discharge it through switching circuit and energy is transferred to DPF which creates plasma. A focused plasma is obtained in DPF device by undergoing three phases (i) Breakdown phase, (ii) Axial acceleration phase and (iii) Radial collapse phase. The good focus obtained in DPF device is observed from the high spike in digital storage oscilloscope (Tektronix TDS 784). Once the good focusing achieved the La 2 O 3 pellet get ionized by argon plasma. The material ions along with argon ions move vertically upward in a fountain shape and material ions are condense on the silicon substrate placed above the top of anode. Conclusion La 2 O 3 nanostructures are deposited on silicon substrates by highly energetic, high fluence ions of material generated in a modified DPF device. XRD establishes that La 2 O 3 nanostructures, having hexagonal structure are deposited. The size of nanograins found using XRD spectra is 16 nm, 15 nm and 10 nm for one, two and three DPF shots respectively. I-V characteristics reveals that the surface become smoother with number of shots. The value of leakage current is small for two and three shots which indicates that the nanostructures are promising candidate for potential application in sensors by designing corresponding electronic device.Acknowledgement Onkar Mangla is grateful to CSIR, New Delhi for the award of Senior Research Fellowship (SRF). XRD spectra of La 2 O 3 nanostructures deposited on silicon substrates with (a) one, (b) two and (c) three DPF shots. Results of I-V Characteristics  I-V characteristics are measured both in accumulation and inversion region.  In one DPF shot there is sudden increase in value of current at lower voltage which indicates the non-uniformity of the deposited nanostructures.  In two and three DPF shots the current and voltage values are obeying a similar behavior which suggest the uniformity of deposited nanostructures.  It is also observed from I-V characteristics that leakage current is almost same for negative and positive bias.  The behavior of I-V characteristics presented here indicates the potential application of La 2 O 3 nanostructures in sensors by designing a corresponding electronic device. Results of XRD Studies  XRD spectra is carried out using D8 Discover.  XRD spectra show Bragg reflections corresponding to [101]; [101] and [102]; [101], [102] and [110] reflections of hexagonal La 2 O 3 for one; two and three DPF shots respectively.  The size of nanostructures found using Scherrer's formula for [101] plane is 16 nm, 15 nm and 10 nm for one, two and three DPF shots respectively.  XRD results shows nanocrystalline behavior of deposited La 2 O 3. References [ 1] P. Pisecny et al, Mat. Sci. Semicond. Processing, Vol. 7 (2004) pp [2] D. Tsoutsou et al, Microelect. Eng., Vol. 85 (2008) pp [3] C. Yang et al, J. Non-Cryst. Solids, Vol. 355 (2009) pp [4] J. W. Mather, Phys. Fluids, Vol. 7 (1964) pp. S28-S34. (b)(a) (c)