Optical and electrical characterizations of Mn doped p-type beta-FeSi2

beta-FeSi2 has attracted increasing attention as a promising material for o ptoelectronic and thermoelectronic devices due to a high optical absorption coefficient (alpha) of about 10(5) cm(-1) near 1.0 eV and its chemical sta bility at higher temperatures. For the future practical use of this materia l in devices, the control of each electrical conductivity type and the impr ovement of the material quality are highly required. Although unintentional ly doped beta-FeSi2 layers formed on n-type Si(1 0 0) by the conventional e lectron-beam deposition (EBD) have typically shown n-type conductivity, the p-type beta-FeSi2 layers were formed by the introduction of Mn impurity us ing ion-implantation at room temperature (RT) and subsequent annealing proc edures. In this study, we aimed to make p-type beta-FeSi2 by implantation o f Mn-55(+) ions into EBD-grown n-type beta-FeSi2 layers/n-Si, where Mn-55() ions were implanted at two different temperatures (T-sub) of RT and 250 d egrees C using an energy and a dose of 300 keV and 2.68 x 10(15) cm(-2), re spectively. Their optical and electrical properties, which ought to be affe cted by implantation and annealing temperatures (T-a2), were investigated b y Raman scattering, optical transmittance, reflectance and van der Pauw mea surements. The results showed that the Mn-55(+) doping with T-sub = RT and higher thermal annealing at T-a2 = 900 degrees C produced p-type layers of good quality with maximum hole mobility of 454.5 cm(2)/Vs at about 65 K. (C ) 1999 Elsevier Science B.V. All rights reserved.