A Ge-Channel Ferroelectric Field Effect Transistor With Logic-Compatible Write Voltage
A Ge-Channel Ferroelectric Field Effect Transistor With Logic-Compatible Write Voltage
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DOI：
10.1109/led.2022.3231123
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发表时间：
2023-02
影响因子：
4.9
通讯作者：
D. Das;Prasanna Venkatesan Ravindran;Chinsung Park;Nujhat Tasneem;Zheng Wang;Hang Chen;W. Chern
中科院分区：
文献类型：
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作者：
D. Das;Prasanna Venkatesan Ravindran;Chinsung Park;Nujhat Tasneem;Zheng Wang;Hang Chen;W. Chern
铁电场效应晶体管（FEFET）在嵌入式存储器应用的先进技术节点处的集成的主要障碍是它们的高的、逻辑不兼容的写入电压。本文中，我们探索Ge作为沟道材料以降低FEFET的写入电压，并且报道了具有± 1.4V的记录低写入电压的p型Ge-FEFET的首次演示，其中在DC下具有0.6V的存储器窗口（MW），并且对于0.2V的MW，写入电压为± 1.4V、± 1.8V和± 2.4V，对于10 $\mu \text{s}$的写入时间，分别为0.5 V和0.8 V。在Ge-pFEFET中观察到的写入电压比Si-pFEFET的写入电压低约50%，与等存储器窗口条件相比[±2.5 V，DC时MW为0.6 V，±3.5 V，MW为0.5 V，写入时间为10 $\mu \text{s}$ ]。由于在Ge界面处形成的Ge的原生氧化物（GeOx）具有比Si平台上的SiO2的介电常数更大的介电常数和更低的厚度，所以实现了Ge-pFEFET中的写入电压的这种显著降低。此外，Ge的较低带隙和较高介电常数可导致对于给定半导体电荷的较低表面电势，从而导致写入电压的进一步降低。此外，我们的Ge-pFEFET显示出107个周期的写入耐久性（如文献中所报道的，Ge-pFEFET的同类最佳），出色的数据保持能力和写后立即读取能力。我们的研究结果表明，锗平台的FEFET嵌入式存储器应用的吸引力。
A major roadblock for the integration of ferroelectric-field-effect transistors (FEFETs) at advanced technology nodes for embedded memory applications is their high, logic-incompatible write voltages. Herein, we explore Ge as a channel material to reduce write voltage of FEFET and report the first demonstration of p-type Ge-FEFETs with record low write voltages of ±1.4 V with a memory window (MW) of 0.6 V at DC and write voltages of ±1.4 V, ±1.8 V and ±2.4 V for MW of 0.2 V, 0.5 V and 0.8 V for a write time of 10 $\mu \text{s}$ , respectively. The write voltages observed in Ge-pFEFETs are ~50% lower than that of a Si-pFEFETs when compared against iso-memory window condition [±2.5 V with a MW of 0.6 V at DC, ±3.5 V for MW of 0.5 V for a write time of 10 $\mu \text{s}$ ]. Such dramatic reduction of write voltages in Ge-pFEFETs is achieved due to the fact that the native oxide of Ge (GeOx), formed at the Ge interface, has a larger dielectric constant and lower thickness than those for SiO2 on the Si platform. In addition, the lower bandgap and higher dielectric constant of Ge may lead to a lower surface potential for a given semiconductor charge, leading to further reduction in the write voltage. Further, our Ge-pFEFETs show write endurance of 107 cycles (the best-in-class for Ge-pFEFETs, as reported in the literature), excellent data retention, and immediate read-after-write capability. Our results indicate the attractiveness of Ge platform for FEFETs for embedded memory applications.