Memory properties of metal/ferroelectric/semiconductor and metal/ferroelectric/insulator/semiconductor structures using rf sputtered ferroelectric Sr0.8Bi2.5Ta1.2Nb0.8O9 thin films

Abstract

Off-axis rf magnetron sputtering has been employed to grow Sr0.8Bi2.5Ta1.2Nb0.8O9 (SBTN) ferroelectric thin films with (115) preferred orientation on SiO2/Si and Si substrates. The lower temperature and the higher oxygen mixing ratios [OMR, O-2/ (Ar+O-2)] used in film processing lead to reduction in the leakage current densities and widening the memory window of the resultant metal-ferroelectric-insulator semiconductor (MRS) structures. The maximum memory windows of the MFIS structures based on 40% OMR SBTN films deposited at 500 degreesC on SiO2/Si substrate are 2.87 and 2.27 V at the bias amplitudes of 10 and 8 V, respectively. With increasing applied voltage, the memory window also increases. The memory window decreases from 2.27 to 1.59 V after the 10(11) switching cycles at a bias amplitude of 8 V. The capacitance difference, DeltaC, between the two states decreases by 48% after retention time of 7000 s. (C) 2003 Elsevier Ltd. All rights reserved.