具有神经形态的硅基异质结构中介电和光电特性的可塑性研究

Plasticity is a basic function in neuroscience for adaptation, processing and learning through synaptic contacts. It brings about the implementation of biologically inspired computing and artificial cognition. A variety of emerging concepts and architectures are being enabled and pursuing new physical effects and future applications. As a result, resistive plasticity alone is not competent for this versatile platform any more. In this context, we will focus on two new types of plasticity, dielectric plasticity and optoelectronic plasticity, in this project. They promise the construction of neuromorphic resonance devices and optoelectronic detectors, of which the tunability is programmable and reconfigurable. The devices herein are designed according to the biological organizations in neuroscience by using silicon based heterojunctions as the key structures supporting the desirable plasticity. We will investigate the key parameters that account for these two types of plasticity and explore the stimuli dependent frequency- and photo-responses along with the semiconductor surface conditions, through which their principles can be understood. Based on these two unique plasticity functions, the approaches to enabling the bio-inspired resonance tuning and stateful optoelectronic logic operations will be implemented in the light of the materials-by-design principle. Our hope is that the theory, architecture and technique achieved in this project are not only helpful for further understanding these two physical effects but also of importance for developing artificial cognition technology.

具有刺激依赖可塑性的材料、结构与器件是获得神经形态硬件的关键环节，它不但为发展类脑运算提供新算法，还为神经形态器件与感知器件的集成提供结合点。近期涌现出的新概念仿生器件不断要求可塑性元件提供更多新颖的物理效应，仅仅依靠刺激依赖的电阻可塑性已不能胜任。本项目针对性地提出了两类可塑性概念，介电与光电响应的可塑性。它们为构建具有神经形态调控的谐振器件与光电探测器件提供了新原理与新架构。本项目将探索采用硅基异质结构的神经形态器件的制备技术；研究这两类可塑性效应中几项关键参数；通过研究“训练”等操作下频率/光电响应特性、半导体表面状态等的变化规律，理解其中的物理机理；基于这两类新效应，探索获得可编程、可重构的可调率以及运算与存储融合的新方法，为发展面向神经形态调控的光电/谐振器件提供原理验证。希望通过澄清这些科学问题，为发展我国具有自主知识产权的、交叉融合的神经形态器件与技术，提供原理、材料与架构。

具有刺激依赖可塑性的材料、结构与器件是获得神经形态硬件的关键环节，近期涌现出的新概念仿生器件不断要求可塑性元件提供更多新颖的物理效应，仅仅依靠刺激依赖的电阻可塑性已不能胜任。本项目针对性地提出了两类可塑性概念，介电与光电响应的可塑性。一方面，通过借鉴生物视神经节结构，我们研制了一类基于硅基异质结的光电突触器件。此类光电器件具有神经形态可调的光响应度；我们通过研究Si半导体表面状态等的变化规律，理解了光电可塑性的物理机理；利用这样的光电响应可塑性，我们研制了一种光控的逻辑与存储融合器件。另一方面，我们基于麦克斯韦－瓦格勒效应，对硅基异质结的介电可塑性进行了理论建模；设计了一类具有“0-3”结构的介质材料，证明了可以通过改变“0”组元的电阻来获得介电常数的刺激依赖可塑性；我们绘制了此类硅基异质结电容可调率的相图，并据此研制了神经形态调控的谐振器件（例如移相器）。这些研究结果有望为发展交叉融合的感存算一体新器件提供新原理、材料与架构。