Effects of ionizing radiation on the memory–based device with Yb2O3 as a charge trapping layer

In this thesis, we have studied the effect of annealing temperature and gamma irradiation on the Al/Al2O3/Yb2O3/Al2O3/n-Si charge trapping memory (CTM) devices. The Al2O3 oxide was utilized as the tunneling oxide and blocking oxide respectively, while Yb2O3 was used as charge trapping oxide. The thin films were deposited by sputtering technique. The samples were then annealed at 200oC 400oC, 600oC, and 800oC in N2 ambient for 40 min, while one sample was kept as-deposited. The crystallinity stucture and surface morphologies of thin films were analysed by X-ray diffraction (XRD) and atomic force microscopy (AFM) techniques. The value of root mean square (RMS) increased with an increase in the annealing temperature. The electrical characteristics of the devices were also analysed through capacitance-voltage(C-V) curves. The capacitancevalue in the accumulation region decreased with an increase in the annealing temperature. The memory window (∆𝑉𝑓𝑏) at several annealing temperature by sweeping voltage of -10V to +10V and back forth has also been studied. The device which was annealed at 200℃ had a largest ∆𝑉𝑓𝑏 8.60 and the highest capacitance at accumulation region than other devices. This could be related to the better charge storage capability of the CTM device. On the other hand, the ∆𝑉𝑓𝑏 at different sweeping voltage between ±8V and ±10V were investigated for several annealing temperature. In addition, the radiation response on CTM device has also been studied intensively through C-V characteristics by using Cs-137 gamma ray source in the dose range of 4Gy to 128Gy. The C-V curves slightly shifted both in the positive and negative voltage direction. This suggesting oxide trapped(ΔNot) and interface trapped(ΔNit) charges were induced by irradiation. It has also been shown that radiation has no significant impact on the memory window. KEYWORDS:CMTdevices, Thinfilms, PDA, Gamma irrradiation, memorywindow.