Modulating The Optical And Electrical Properties Of Nanomaterial By Ion Beam

Recently, ion implantation was wildly used in material doping and surface treatment, as its excellent advantage including exact controllability, high repeatability, and good compatibility. This thesis embarks from the ion implantation technology, take high-performanc devices as the goal. We demonstrated a highly reproducible bipolar resistance switching in W-implanted silica film (WNPs-SiO2). At the same time, we also demostrated a method to modulate the threshold voltage (Vth) of oxide nanowire field-effect transistors (FET) by Ga+ ion irradiation. The mainly contents of this thesis were listed as follow:Fristly, for resistance random access memory (RRAM), embedding metal nanoparticles in switching layer is beneficial to improve the stability of RRAM device and reduce the forming voltage. In the third chapter of this thesis, we perapared WNPs-SiO2 composite film by ion implantation. The I-V curve exhibits that the WNPs-SiO2 film have a bipolar resistance switching behavior. Through modulating the implantation parameter, the proformance of the WNPs-SiO2 based RRAM device was optimized, and the best implantation dose is 5 x 1015 ions/cm2. Under this implantation dosage, the WNPs-SiO2 based RRAM exhibit good performance, the ON/OFF ratio is close to 106. The retention test exhibits that the resistances of both LRS and HRS have no degradation for at least 104 s. The endurance test shows that the device also can also switch normally after 400 programming. According to TEM and XPS analysis, we explained the resistance switching mechanism of the WNPs-SiO2 based RRAM.Secondly, metal ion implantation is a nomal method for fabricating metal NPs array. Generally speaking, after ion implantation, the metal ions distribute in the substrate, these metal ions will agglomerate into metal NPs by subsequent annealing. In the third chapter of this thesis, we perapared Ag NPs array by ion implantation and subsequent annealing. Through adjusting the implantation parameter and thermal annealing process for modulating the size and spacing of the NPs. Then, the 4-nitrobenzenethiol (4-NBT) and Rhodamine 6G (R6G) were selected as the Raman molecules to explore the SERS properties of the Ag-implanted silicon substrate.Thirdly, for the field-effect transistor, both E-mode and D-mode FET have important application in the integrated circuits field. So, modulating the threshold volatge of FETs is an interesting research direction. The researchers reported that the Vth modulation can be realized by doping and surface treatment. In the fourth chapter of this thesis, we demonstrated a method to modulate the threshold voltage of oxide nanowire field-effect transistors (FET) by Ga+ion irradiation. After Ga+ ions irradiation, the Vth of the oxide nanowire FET shift in the negative gate voltage direction. After irradiation, the Vth of In2O3 nanowire FET shift from 10 V to IV, and the carrier mobility increaed form ?56 to ?68 cm2/(V·s). The decrease of threshold voltage indicate that the device have a low operation voltage, this is beneficial to fabricate low-power dissipation devices. Finally, through analyzing the TEM of irradiated nanowire and unirradiated naowire, we explained the mechanism about the threshold voltage shift. In addition, the optical property of single cadmiumsulfide nanowire implanted by N+ ions has been researched.