针对多层MoS2的低能等离子体可控掺杂机理及原位缺陷修饰研究

Compared with single-layer (SL) MoS2, the density of states of multilayer (ML) MoS2 is three times that of SL MoS2 at the conduction band minimum, which will lead to considerably high drive currents and multiple conducting channels. Therefore, considering the practical applications, ML MoS2 is more suitable for the fabrication of photoelectric devices. The current ML MoS2-based photoelectric devices exhibit relatively poor values of figures of merit. In order to address this issue, doping is required to generate P-N junction type MoS2 with the built-in potentials to separate the photogenerated charges, enhance the output photovoltage and inhibit the reverse saturated dark current. Plasma doping is a new doping method for MoS2, but doping controllability is still a problem to be solved. In this research, low energy and pulse-type ALD plasma mode is utilized to dope ML MoS2. The plasma pulse time in each ALD cycle and the interval time of each cycle can be both controlled by sub-seconds. As a result, the doping concentrations of ML MoS2 can be precisely regulated by ALD cycles and its photoluminescence can be efficiently modulated. In addition, the introduced defects during doping can be in situ modified by ALD thermal mode and the optical and electrical properties of ML MoS2 can be further corrected.

相对于单层MoS2而言，多层MoS2在导带最低能级处有三倍于单层MoS2的态密度，能承载更高的驱动电流且具有多层导电沟道，因此从实际应用角度考虑，多层MoS2更适用于光电器件的制备。目前多层MoS2在光电器件等应用领域的制约因素是其品质因素较低，为解决这一问题，需对MoS2进行局域掺杂以形成P-N结，通过内建电势分离光生电子-空穴对、增大输出光电压并抑制反向饱和暗电流。等离子体掺杂是目前针对MoS2的新型掺杂方式，但掺杂可控性却是函待解决的问题。本研究提出利用ALD等离子体模式，对多层MoS2进行低能脉冲式等离子体掺杂，亚秒级控制单一ALD循环中等离子体的脉冲时间及各循环间的时间间隔，通过“ALD循环数”对“多层MoS2掺杂浓度”的精确调控，实现对多层MoS2光致发光性能的有效调节，并利用ALD热生长模式对掺杂引入的缺陷进行原位修饰，进一步修正多层MoS2的光学及电学性能。

多层MoS2具有多层导电沟道，且在导带最低能级处有三倍于单层MoS2的态密度，因此相对于单层MoS2而言能承载更高的驱动电流，从实际应用角度考虑更适用于光电器件的制备。目前多层MoS2在光电器件等应用领域的制约因素是其品质因素较低，为解决这一问题，需对MoS2进行局域掺杂以形成P-N结，通过内建电势分离光生电子-空穴对、增大输出光电压并抑制反向饱和暗电流。等离子体掺杂是目前针对MoS2的新型掺杂方式，但掺杂可控性却是函待解决的问题。本研究利用ALD等离子体模式，对多层MoS2进行低能脉冲式等离子体掺杂，亚秒级控制单一ALD循环中等离子体的脉冲时间及各循环间的时间间隔，通过“ALD循环数”对“多层MoS2掺杂浓度”的精确调控，实现对多层MoS2光致发光性能的有效调节，并利用ALD热生长模式对掺杂引入的缺陷进行原位修饰，进一步修正多层MoS2的光学及电学性能。本研究的成果可为MoS2的微电子和光电子应用提供理论基础和技术支撑。