There is a constant need for Hall-effect magnetic sensors with lower noise and lower offset for the high accuracy analog applications driven primarily by industrial and automotive markets, for example, high dynamic range current sensing for battery management in electric vehicles. Graphene-based Hall sensors (GHSs) demonstrate low thermal noise due to their high carrier mobility but suffer from large low-frequency flicker noise and offset limiting the prevalent low-frequency applications. In this paper, we present the results of a recently proposed gate modulation scheme for GHSs that uses dynamic ambipolar operation to up-convert the input magnetic signal to higher modulating frequencies while the offset and flicker noise remain spectrally unchanged and thus enabling thermal noise limited performance. We implement a prototype GHS using a scalable fabrication process with CVD graphene transferred on to silicon-oxide and followed by standard thin film and subsequent photolithographic processes. The measurement results confirm the effectiveness of dynamic ambipolar gate modulation technique in producing low offset of −524μT- 524\,\,\mu \mathrm{T} in conjunction with three orders of magnitude estimated improvement in the low frequency noise performance.

中文翻译：

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用于减少石墨烯霍尔效应传感器中的偏移和闪烁噪声的双极栅极调制技术


主要由工业和汽车市场驱动的高精度模拟应用（例如，用于电动汽车电池管理的高动态范围电流传感）始终需要具有更低噪声和更低偏移的霍尔效应磁传感器。基于石墨烯的霍尔传感器 (GHS) 由于其高载流子迁移率而表现出低热噪声，但存在较大的低频闪烁噪声和偏移，限制了普遍的低频应用。在本文中，我们介绍了最近提出的 GHS 栅极调制方案的结果，该方案使用动态双极操作将输入磁信号上变频到更高的调制频率，同时偏移和闪烁噪声在频谱上保持不变，从而实现热噪声限制性能。我们使用可扩展的制造工艺实现了原型 GHS，将 CVD 石墨烯转移到氧化硅上，然后进行标准薄膜和后续光刻工艺。测量结果证实了动态双极栅极调制技术在产生 −524μT- 524\,\,\mu \mathrm{T} 的低偏移方面的有效性，以及低频噪声性能的三个数量级的估计改进。