基于金属—半导体界面光电效应的多功能信息存储器研究

发布时间：2018-04-16 04:30

本文选题：阻变效应 + 持续光电导　；参考：《中国科学院宁波材料技术与工程研究所》2016年博士论文

【摘要】：结构简化,功能化和多样化是后摩尔时代电子信息技术发展的主要趋势。光电多功能集成器件通过光和电对简单器件电阻的调控,实现信息处理功能集成化和多样化,有利于增加器件功能密度并实现数据并行传输及运算。然而这其中最根本的科学问题是如何利用光和电对简单界面势垒实现连续、精准与可逆调控。本文选用简单的金属-半导体界面,利用光和电场调控界面电阻,实现光电多功能器件,对光信号和电信号进行处理与存储,进一步提高数据的并行传输与处理能力。具体如下:利用磁控溅射技术制备了光感半导体氧化铈(CeO_(2-x))和氧化锌(ZnO)半导体薄膜,并通过费米能级匹配选择合适的金属电极在半导体-金属界面构建肖特基势垒,系统研究光和电场对该界面势垒电导的调控行为及规律,探索光电可控的金属-半导体界面作为器件单元实现光电多功能集成的思路与方法。一、选用光敏材料CeO_(2-x)作为功能层,与费米能级更低的金属Al构成肖特基势垒,通过光脉冲调控CeO_(2-x)/AlO_y/Al界面空间电荷区内氧空位的电荷状态,进而调控界面电导。发现该结构的光电导具有持续性,最大持续可见光/暗电导比值为~104,持续光响应度为1A/W,并在室温下104 s时间内基本保持不变。进一步研究发现持续光电导与光照强度和时间呈线性关系,与理论分析一致。而且具有从紫外到可见的宽谱响应行为,并且随着光波长的增加,光电导减小。利用光电导的持续性及其与光照强度、波长和光照时间的响应关系,实现了CeO_(2-x)/AlO_y/Al光响应界面对宽频光信号的探测、解码、简单算术运算与存储的多功能的集成。二、进一步研究光脉冲和电压共同对ITO/CeO_(2-x)/AlO_y/Al结构界面电阻的调控行为及规律。实现了稳定的双极性电致阻变行为,正向扫描电压下电阻降低,负向扫描电压下电阻升高,开光比大于10。当利用光对电致阻变行为进行调控时,发现施加一个光脉冲后,电致阻变过程中的高低阻值分别降低10倍左右,说明光和电均可以非易失性地调控电阻转变。基于此,以光脉冲和正向电压脉冲作为输入信号,以非易失的电阻作为输出信号,该光电可控的金属-半导体界面可实现非易失性的‘与门’逻辑的功能,并且通过光调控初始电阻状态,可以实现‘与门’向‘或门’逻辑功能的转换,即非易失可重构逻辑门。进一步引入‘初始化’操作,实现三输入的复杂非易失可重构逻辑操作。这些逻辑操作可反复擦写,在室温下每种逻辑关系的设置和逻辑输出值在103 s时间内基本保持不变,可用于数据原位存储。三、为进一步提高半导体-金属界面的功能性,在上述研究的基础上,选用典型的光电材料以及阻变材料氧化锌(ZnO)作为功能层,选用费米能级更低的掺铌钛酸锶(NSTO)作为电极形成肖特基势垒,提出利用持续光电导效应模拟神经突触的基本行为和功能:通过施加一个光脉冲,使电流迅速增加,然后持续衰减,模拟神经的后突触兴奋电流;连续施加两个脉冲,第二个脉冲的峰值大于第一个脉冲的峰值,模拟神经突触的双脉冲易化行为;在相同个数的脉冲下,通过增加脉冲时间宽度模拟了短期记忆和长期记忆的突触功能。即实现了光电仿生突触。另外,以光和电场作为输入信号,利用单一光突触的记忆行为实现非易失性可重构逻辑操作,进一步构建光突触阵列来模拟对图像信息的短期、长期记忆与图像识别的功能。
[Abstract]:To simplify the structure, function and diversity is the main trend of electronic information technology in the development of post Moore era. Multifunctional photoelectric integrated device by controlling the optical and electrical devices for simple resistance, realize the information processing function of integration and diversification, help to increase the device function density and realize data parallel transmission and operation. However, the most scientific problems it is how to use the light and electricity to achieve continuous simple interface barrier, precise and reversible regulation. The simple metal semiconductor interface, using optical and electrical control interface resistance, realize multifunctional photoelectric device, processing and storage of optical signals and electrical signals, to further improve the parallel transmission and data processing capability. The details are as follows: optical semiconductor ceria were prepared by magnetron sputtering technique (CeO_ (2-x)) and Zinc Oxide (ZnO) semiconductor thin film, and the Fermi level matching Select the appropriate metal electrode in a semiconductor metal interface construction of Schottky barrier regulation system of light and electric field on the interfacial barrier conductance and the law, explore the photoelectric controllable metal semiconductor interface as a multifunctional photoelectric device unit implementation ways and integration method. A selection of photosensitive material, CeO_ (2-x) as the functional layer a Schottky barrier metal Al, and the Fermi level is lower, the optical pulse modulation of CeO_ (2-x) /AlO_y/Al interface state charge within the space charge region of oxygen vacancy, thereby regulating the interface conductance. The structure has found photoconductivesemiconductor continuity, maximum continuous visible light / dark conductivity ratio is ~104, continuous light response degree is 1A/W at room temperature, and 104 s time remained basically unchanged. Further study found that persistent photoconductivity and light intensity and time is linear, consistent with the theoretical analysis. It is also featured by UV To see the wide spectrum response behavior, and with the increase of the wavelength of light, the photoconductivity decrease. Persistent photoconductivity and use intensity and light response relationship between wavelength and illumination time, the CeO_ (2-x) interface of broadband optical signal detection, the optical response of /AlO_y/Al decoding, integrated multi function simple arithmetic operation and storage. Two, further study on pulse and voltage of ITO/CeO_ (2-x) Regulation of behavior and law of interface structure of /AlO_y/Al resistance. To achieve a stable bipolar electro resistive behavior, resistor scanning voltage lower, negative scanning voltage resistance increases, the opening ratio is greater than 10. when using light the regulation of the electrical resistance change behavior, found that applying a pulse of light, high and low resistance electrical resistance change in the process were reduced by about 10 times, that light and electricity can nonvolatile resistance change regulation. Based on this, to light Positive pulse and pulse voltage as the input signal, the non resistance volatile as output signals, the photoelectric controllable metal semiconductor interface can realize non-volatile 'and' logic function, and through the light regulation of initial resistance state, can achieve "conversion gate" to "or" logic function, i.e. the non-volatile reconfigurable logic gate. Further introduce the 'initialize' operation, to achieve three input complex non-volatile reconfigurable logic operation. These logic operations can be repeatedly erased, at room temperature for each logical relation set and logic output value remained unchanged at 103 s time, and can be used for data storage in three. In order to further improve the function of semiconductor and metal interface, on the basis of the above research, selection of typical optoelectronic materials and resistive materials Zinc Oxide (ZnO) as the functional layer, the Fermi level lower doped NB: SrTiO3 (NSTO) as the electrode forming a Schottky barrier, put forward the basic behavior and synaptic function simulation using continuous photoconductive effect: by applying a pulse of light, the current rapid increase, then decreasing, the simulation of neural synaptic excitation current; continuous applying two pulse, second pulse peak the first pulse peak, double pulse simulation of synaptic facilitation behavior; in the same number of pulses, by increasing the simulation of synaptic function in short-term and long-term memory. The pulse width of light electric bionic synapse. In addition, as light and electric field as the input signal, realize nonvolatile can reconfigurable logic operation using the memory behavior of single light synapses, further build synapse array to simulate the image information in the short term, long-term memory and image recognition function.

【学位授予单位】：中国科学院宁波材料技术与工程研究所
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TP333

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