Device and material reliability of 2-dimensional materials, especially CVD-grown MoS₂, has remained un-addressed since 2011 when the first TMDC transistor was reported. For its potential application in next generation electronics, it is imperative to update our understanding of mechanisms through which MoS₂ transistors’ performance degrades under long-term electrical stress. We report, for CVD-grown monolayer MoS₂, results on temporal degradation of material and device performance under electrical stress. Both low and high field regimes of operation are explored at different temperatures, gate bias and stress cycles. During low field operation, current is found to saturate after hundreds of seconds of operation with the current decay time constant being a function of temperature and stress cycle. High field operation, especially at low temperature, leads to impact ionization assisted material and device degradation. It is found that high field operation at low temperature results in amorphization of the channel and is verified by device and kelvin probe force microscopy (KPFM) analyses. In general, a prolonged room temperature operation of CVD-grown MoS₂ transistors lead to degraded gate control, higher OFF state current and negative shift in threshold voltage (V_T). This is further verified, through micro-Raman and photoluminescence spectroscopy, which suggest that a steady state DC electrical stress leads to the formation of localized low resistance regions in the channel and a subsequent loss of transistor characteristics. Our findings unveil unique mechanism by which CVD MoS₂ undergoes material degradation under electrical stress and subsequent breakdown of transistor behavior. Such an understanding of material and device reliability helps in determining the safe operating regime from device as well as circuit perspective.

自2011年报道第一个TMDC晶体管以来，二维材料（尤其是CVD生长的MoS _2）的器件和材料可靠性一直未得到解决。对于其在下一代电子产品中的潜在应用，必须更新我们对MoS ₂晶体管在长期电应力下性能下降的机理的了解。我们报告，对于CVD生长的单层MoS ₂会导致在电应力下材料和设备性能随时间下降。在不同的温度，栅极偏置和应力周期下，都研究了低场和高场工作状态。在低场操作期间，发现电流在数百秒的操作后达到饱和，电流衰减时间常数是温度和应力周期的函数。高场操作，尤其是在低温下，会导致碰撞电离辅助材料和器件性能下降。发现低温下的高场操作会导致通道的非晶化，并通过设备和开尔文探针力显微镜（KPFM）分析进行了验证。通常，CVD生长的MoS ₂在室温下可长时间运行晶体管会导致栅极控制性能下降，OFF状态电流增大以及阈值电压（V _T）发生负移。通过微拉曼光谱和光致发光光谱进一步证实了这一点，这表明稳态的直流电应力导致沟道中局部低电阻区域的形成，并随后导致晶体管特性的损失。我们的发现揭示了独特的机制，通过该机制，CVD MoS ₂在电应力作用下会发生材料降解，并随后破坏晶体管的性能。对材料和设备可靠性的这种理解有助于从设备以及电路的角度确定安全的工作状态。