Detailed structural analysis of Ce doped Si thin films

A diluted magnetic semiconductor, Si:Ce thin film was prepared by vacuum ev aporation using electron beam guns. As-deposited thin film was n-type condu ction due to its amorphous nature. It shows a normal semiconductor like rho -T behavior with a diamagnetic property. By annealing at 973 K, the conduc tion type change to p-type and the resistivity remarkably decreases by thre e orders of magnitude below 30 K. Change in the magnetic susceptibility aga inst the measurement temperature at the low magnetic field (750 Oe) exhibit s spin glass like behavior showing cusp around 40 K. We also confirm an ext remely large magneto-resistance below the spin glass temperature. To unders tand the relationship between the magnetic behavior and the micro-structure , detailed structural analyses were performed. Although no precipitation wa s confirmed by electron transmission diffraction (TED) analysis, widely dis persed black regions with the diameter of around 10nm were clearly observed . TED and TEM reveal that the crystal structure of the black region is iden tical to that of Si with stacking faults and twins. This paper describes th at the anomalous magneto-transport behavior of annealed Si:0.5 at% Ce is st rongly related to micro-structure. (C) 2001 Elsevier Science B.V. All right s reserved.