Radiation effects and low frequency noise in black phosphorus transistors
Black phosphorus (BP) is a promising two-dimensional (2D) semiconductor material for future CMOS technology. Its tunable band gap from 0.3 eV in bulk samples to 1.5 eV for monolayers and high mobility overcomes the disadvantages of other 2D materials. HfO2 is a standard dielectric material in advanced MOSFETs, it is reasonable that HfO2 may also be utilized in mature, commercial BP devices. To date, little is known about the radiation effects, low frequency noise or the single-event vulnerability of the BP MOSFETs with HfO2 gate oxides. In this work, we evaluate the radiation response of BP pMOSFETs with HfO2 gate oxides under gate-bias conditions. Low-frequency noise measurements are employed to provide insight into the nature of the defects that affect the reliability and radiation response of these devices, and density functional theory (DFT) calculation is used to identify possible defect candidates. The temperature-dependent noise spectra show changes in defect distributions. O vacancies in HfO2 and hydrogen transportations near the BP/HfO2 interface play a significant role in determining the radiation response and low-frequency noise of these BP/HfO2-based devices. These dominating defects limit the device radiation response and reliability. Additionally, laser-induced SETs are observed in BP MOSFETs. Peak SET transients are observed when the laser is on at the center of the gate. The dependence of the SETs on the drain bias dominate over the overdrive voltage, which can be explained by shunt effect.