Ion Beam Induced Epitaxial Crystallization of Single Crystalline 6H-SiC
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V. HEERA*, R. KOGLER*, W. SKORUPA* AND E. GLASER** * Research Center Rossendorf Inc., P.O.B. 510119, D-01314 Dresden, Germany ** FSU Jena, Institute of Solid State Physics, Max-Wien-Platz 1, D-07743 Jena, Germany ABSTRACT
For the first time, ion beam induced epitaxial crystallization (IBIEC) has been found in SiC. The effect of 300 keV Si+ irradiation through an amorphous surface layer in single crystalline 6H-SiC at 477_+50 C has been investigated by RBS/C and XTEM. A shrinkage of the amorphous layer was found after ion irradiation at this temperature which is caused by both an ion dose independent thermal regrowth of about 20 nm and an additional ion beam induced epitaxial crystallization with a rate of about 1.5 nm/ 1016 cm"2 . INTRODUCTION
Silicon carbide (SiC) exists in many polytypes [1] and is a promising wide band gap semiconductor for high temperature, high power and high speed electronic application [2,3]. However, single crystalline bulk material with high quality sufficient for industrial purposes has been available only recently as 4H- and 6H-polytype 1" wafers [4]. Compared to silicon, relatively little is known about the formation and annealing of implantation damage in SiC. The critical energy density for amorphization by ion implantation at room temperature was found to be about 2. 1021 keV/cm3 [5]. Post implantation annealing at 300'C led to an appreciable recovery of the irradiation damage only if the amount of deposited damage energy was less than the critical value. It has been shown by several authors [6,7,8,9] that the complete regrowth of implantation produced amorphous SiC layers by solid phase epitaxy (SPE) needs temperatures higher than 14001C. Moreover, a perfect SPE regrowth, without visible remaining damage, occurred only at 1800°C [7]. However, at such temperatures SiC begins to sublimate and dopant atoms are redistributed. It is known that ion irradiation may be used for low temperature recrystallization of amorphous surface layers in some semiconducters. The ion beam induced epitaxial crystallization (IBIEC) has been extensively investigated in silicon material [10]. It was shown that IBIEC can take place in Si already at a temperature of 150°C, whereas a temperature of 5500C is necessary for thermally induced SPE in this material. The IBIEC effect has been found to occur also in the compounds Ge1 1Six [11], GaAs [12], InP, NiSi 2, CoSi 2 [13], A120 3 [14] and BP [15] at temperatures much lower than necessary for thermal SPE. The recent results on IBIEC of BP at 4000C are of particular interest, because, similar to SiC, BP is a wide band gap semiconductor which usually needs processing temperatures far beyond 1000°C. Encouraged by the sucess in ion beam induced recrystallization of several semiconductors, we have studied the effect of 300 keV Si+ ion irradiation through an amorphous surface layer in single crystalline 6H-SiC at a temperature of 477°C by Rutherford backscattering/ channeling (RBS/C) and cross-section transmission electron microscopy (XTEM). 387 Mat. Res. Soc. Symp.
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