ACS Applied Materials&Interfaces|面向神经形态工程的基于高掺杂硅衬底的非晶氮化硼 ...

文章链接：https://dx.doi.org/10.1021/acsami.0c07867

摘要

在本研究中，一种CMOS兼容的Ti/a-BN/Si器件的电阻开关和突触特性被研究用于神经形态系统。在正SET操作中，可以观察到电阻的逐渐变化。该操作非常适合于基于硬件的神经形态系统中的突触器件。等值面电荷密度图和实验结果表明，钛离子由互扩散形式产生的导电路径是有限的，而硼空位可以帮助形成一条导电路径。负SET操作导致硼空位的形成能显著降低，从而增加低阻状态下的导电性，这可能与RESET失败和持久性差有关。8个多态冲瞬态特性、增强和抑制特性以及良好的保留特性也说明由于电导的逐渐调制，SET操作更适合于突触器件。此外，通过将Ti/a-BN/Si器件中测量数据的电导值作为神经网络的突触部分来检验模式识别的准确性。基于增量电压脉冲方案的SET操作中线性对称突触权值更新保证了更高的模式识别精度。

In this study, the resistive switching and synaptic properties of a complementary metal-oxide semiconductor compatible Ti/a-BN/Si device are investigated for neuromorphic systems. A gradual change in resistance is observed in a positive SET operation in which Ti diffusion is involved in the conducting path. This operation is extremely suitable for synaptic devices in hardware-based neuromorphic systems. The isosurface charge density plots and experimental results confirm that boron vacancies can help generate a conducting path, whereas the conducting path generated by a Ti cation from interdiffusion forms is limited. A negative SET operation causes a considerable decrease in the formation energy of only boron vacancies, thereby increasing the conductivity in the low-resistance state, which may be related to RESET failure and poor endurance. The pulse transient characteristics, potentiation and depression characteristics, and good retention property of eight multilevel cells also indicate that the positive SET operation is more suitable for a synaptic device owing to the gradual modulation of conductance. Moreover, pattern recognition accuracy is examined by considering the conductance values of the measured data in the Ti/a-BN/Si device as the synaptic part of a neural network. The linear and symmetric synaptic weight update in a positive SET operation with an incremental voltage pulse scheme ensures higher pattern recognition accuracy.