Surface and Interface Characterization of Ion Beam Re-crystallized Si
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Surface and Interface Characterization of Ion Beam Re-crystallized Si P.K. Sahoo1, B. Satpati2, S. Dey1, P.V. Satyam2, T. Som2, V.N. Kulkarni1, 3 1
Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208 016, India. Institute of Physics, Bhubaneswar 751 001, India. 3 Center for Superconductivity Research, Dept. of Physics, Univ. of Maryland, College Park. 2
ABSTRACT In the present work we have studied efficacy of ion beam induced epitaxial crystallization (IBIEC) to recover amorphous layers (300 - 350 nm) produced by MeV Kr ions in Si(100) and studied the associated changes occurring on surface and interface of the recrystallized region. IBIEC experiments were carried out at sample temperatures in the range of 200 - 400oC using 1 MeV N+ ion beam. Rutherford backscattering-Channeling technique showed planar and gradual recovery of the amorphous layer as a function of temperature. Transmission electron microscopy measurements show good crystalline structure of the recovered region at 400oC while at lower temperatures nano-crystalline Si formation embedded in the amorphous structure is evident. The surface topography studied by atomic force microscopy shows development of islands after IBIEC. The rms roughness is around 0.5 nm and average height of the islands is found to be 1.8 nm. The observed epitaxial growth and the surface topographical features have been correlated. INTRODUCTION Low temperature re-crystallization of Si and other materials used in microelectronics and photonic devices can be advantageous in device fabrication technology due to reduction in undesired diffusion of dopants. Ion beam induced epitaxial crystallization (IBIEC) is a special technique which is being explored to achieve epitaxy at much lower temperatures than those used in conventional solid phase epitaxy (SPE) [1]. Low processing temperature, layer-by-layer amorphization, dynamic annealing, possibilities of producing better quality crystal, and dopant activation in case of compounds semiconductors [2,3] are the unique features of IBIEC. Most of the IBIEC works reported so far has been carried out on the amorphous layer produced by heavy ion species like Si, Au, Ag, Kr, Ar etc. of energies 100 - 300 keV [4-7]. The application of MeV ion implantation and crystallization is very important in this era of rapidly changing technology. Production of buried amorphous layers, dense dislocations in buried layers, silicon-on-insulator (SOI) structure formation and production of various types of defects at different depths [8] are the main features of MeV ion implantation which have potential for novel applications in semiconductor industries. In our previous work, we have shown that epitaxial recovery of MeV heavy ion implanted thick amorphous Si films can be achieved by IBIEC at sample temperatures much lower as compared to the conventional ones used in SPE, and discussed these results on the basis of electronic (Se) and nuclear energy loss (Sn) phenomena [12]. In the present work we are reporting the topographical and m
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