Radial Growth Model for Conical Nanobridge in Resistive Switching Memory Devices
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Exposure Light Wavelength Effects on Charge Trapping and Detrapping of nc-MoOx Embedded ZrHfO High-k Stack Xi Liu1,2, Yue Kuo1, and Tao Yuan2 1
Thin Film Nano & Microelectronics Research Laboratory, Department of Artie McFerrin Chemical Engineering, Texas A&M University, College Station, TX 77843-3122 2 Deptartment of Industrial and Systems Engineering, Ohio University, Athens, OH 45701 ABSTRACT The influence of the red and green LED light exposure on the memory function of the nanocrystalline MoOx embedded ZrHfO high-k gate dielectric has been investigated. Since the performance of the device is mainly dependent on the hole trapping and detrapping mechanisms, the light exposure affects the hole generation, transfer, and storage to and in the dielectric structure. Both the charge storage capacity and the leakage current were increased from the light exposure. The Coulomb blockade phenomenon in the leakage current density vs. gate voltage curve disappears under the light exposure condition. The light exposure effect is potentially important for practical application of the device. INTRODUCTION Compared with the conventional poly-Si floating gate memory device, the nanocrystals embedded dielectric structure can be more reliable because each nano dot is separated from others to avoid the total charge loss from a single leakage path in the dielectric structure [1–3]. In addition, it is necessary to replace the SiO2 gate dielectric layer with a high-k gate dielectric material of the same equivalent oxide thickness (EOT) in the nano-size MOSFET to lower the leakage current, to decrease the operating voltage, and to improve the data retention efficiency [4–6]. Among available metal oxide high-k dielectric materials, the Zr-doped HfO2 (ZrHfO) has many advantages with respect to the bulk and interface properties, such as the high crystallization temperature, low interface state density, and large effective k value [5,7–11]. Recently, various conductive and semiconductive materials, such as Si, RuO, ITO, ZnO, and MoOx, have been prepared into the nanocrystalline form and embedded in high-k films as the electron- or hole-trapping media in the memory devices [4,12–17]. Although the nanocrystals embedded high-k dielectric structure is potentially important in memory applications, some physical properties are not well understood. In particular, the light exposure effects on the performance of the charge storage are usually neglected until very recently [18,19]. The charge trapping and detrapping properties of capacitors with the ZrHfO gate dielectric are generally insensitive to light exposure. However, when the nanocrystalline ZnO (nc-ZnO) dots are embedded in the ZrHfO layer, the memory functions are affected by the light exposure process because of changes of the electron-hole generation and transfer mechanisms [18,19]. This phenomenon is potential important in various electronic and optoelectronic applications. Furthermore, there is lack of information on the influence of the individual wavelength on the charge transfer mech
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