%0 Journal Article
%T Deposition and Characterization of CVD-Grown Ge-Sb Thin Film Device for Phase-Change Memory Application
%A C. C. Huang
%A B. Gholipour
%A K. Knight
%A J. Y. Ou
%A D. W. Hewak
%J Advances in OptoElectronics
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/840348
%X Germanium antimony (Ge-Sb) thin films with tuneable compositions have been fabricated on SiO2/Si, borosilicate glass, and quartz glass substrates by chemical vapour deposition (CVD). Deposition takes place at atmospheric pressure using metal chloride precursors at reaction temperatures between 750 and 875¡ãC. The compositions and structures of these thin films have been characterized by micro-Raman, scanning electron microscope (SEM) with energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD) techniques. A prototype Ge-Sb thin film phase-change memory device has been fabricated and reversible threshold and phase-change switching demonstrated electrically, with a threshold voltage of 2.2¨C2.5£¿V. These CVD-grown Ge-Sb films show promise for applications such as phase-change memory and optical, electronic, and plasmonic switching. 1. Introduction There is currently worldwide interest in the development of the next generation of computer memory, fuelling research in new materials which can be used to potentially store vast amounts of information. Phase-change random access memory (PCRAM) has attracted considerable interest as a candidate for the next generation of nonvolatile devices which will meet current and future needs of higher density, power consumption, and operation speed [1, 2]. Ternary Ge2Sb2Te5 (GST) compounds are widely regarded as the most commercially viable and practical phase-change family of materials for this application. These materials are currently being trialled commercially, and processes which deposit GST films by RF sputtering are being implemented into production lines [3]. Chemical vapour deposition techniques are expected to play a role in device fabrication and recently metal organic chemical vapour deposition (MOCVD) process has been applied to deposit GST materials in submicron cell pores [4]. In addition, the atomic layer deposition (ALD) process, which uses a mixture of metal organic and metal chloride precursors, has been reported for the fabrication of GST thin films. However, the contamination of O, H, C, and Cl atoms was reported as a consequence of the low deposition temperature [5]. There remains however many challenges [6] which include the need to control device-to-device variability and undesirable changes in the phase-change material that can be induced by the fabrication procedure. In addition the relatively long crystallization time of GST (~ hundreds nanoseconds) limits the ultimate operation speed of the PCRAM device [7]. A confined cell structure where the phase-change material is formed inside a
%U http://www.hindawi.com/journals/aoe/2012/840348/