Xinzhong Duo

Evolution of hydrogen and helium co-implanted single-crystal silicon during annealing

H+ was implanted into single-crystal silicon with a dose of 1×1016/cm2 and an energy of 30 KeV, and then He+ was implanted into the same sample with the same dose and an energy of 33 KeV. Both of the implantations were performed at room temperature. Subsequently, the samples were annealed in a temperature range from 200 to 450 °C for 1 h. Cross-sectional transmission electron microscopy, Rutherford backscattering spectrometry/channeling, elastic recoil detection, and high resolution x-ray diffraction were employed to characterize the strain, defects, and the distribution of H and He in the samples. The results showed that co-implantation of H and He decreases the total implantation dose, with which the surface could exfoliate during annealing. During annealing, the distribution of hydrogen did not change, but helium moved deeper and its distribution became sharper. At the same time, the maximum of the strain in the samples decreased a lot and also moved deeper. Furthermore, the defects introduced by ion i...

Preparation and characterization of MgO thin films by a simple nebulized spray pyrolysis technique

A simple nebulized spray pyrolysis method has been applied to prepare MgO thin films with (200) preferential orientation on (100) Si substrates by using magnesium acetate as starting reactants. The experimental results revealed that the substrates temperature and the oxygen flow played important roles in the formation of (200) oriented MgO film. The surface morphology and some properties of the prepared MgO thin films were examined by atomic force microscopy, transmission electron microscopy, X-ray diffraction and spread resistance processing technique.

Preparation and Characterization of MgO Thin Films by a Novel Sol-Gel Method

MgO thin films have been prepared on Si substrates by a novel and simple sol-gel method using magnesium nitrate and collodion as starting material. Solutions consisting of magnesium nitrate in a mixture of collodion and ethanol were spin-coated onto silicon substrates. It was found that collodion was a necessary component to form stable sols and the crystallization and structures were clearly dependent on the amount of the collodion and the annealing temperature. The MgO thin films with good crystallization were obtained after annealing at 800°C. Meanwhile, the microstructure of the MgO films was examined by transmission electron microscopy and atomic force microscopy.

Comparison between the different implantation orders in H+ and He+ coimplantation

H + and He + were implanted into single crystals in different orders (H + first or He + first). Subsequently, the samples were annealed at different temperatures from 200 ◦ Ct o 450 ◦ C for 1 h. Cross sectional transmission electron microscopy, Rutherford backscattering spectrometry and channelling, elastic recoil detection were employed to characterize the defects and the distribution of H and He in the samples. Furthermore, the positron traps introduced by ion implantation and annealing were characterized by slow positron annihilation spectroscopy. Both orders in the coimplantation of H and He have the ability to decreases the total implantation dose after annealing. No bubbles or voids but cracks and platelets, were observed by cross sectional transmission electron microscopy. The different implantation orders affect the density of interstitial atoms and positron traps.

Comparison of Cu gettering to H+ and He+ implantation-induced cavities in separation-by-implantation-of-oxygen wafers

Well-defined bands of cavities have been formed beneath the buried oxide (BOX) layer of two sets of separation-by-implantation-of-oxygen (SIMOX) wafers by H+ and He+ implantation. The gettering of Cu impurities, which were implanted into the top Si layer at different doses (5×1013, 5×1014, and 5×1015/cm2), to the cavities has been studied by secondary ion mass spectroscopy and cross-sectional transmission electron microscopy. The results indicated that the cavities induced either by H+ or He+ implantation are effective gettering centers for Cu in SIMOX wafers, and up to 4×1015/cm2 Cu has diffused through the BOX layer and been captured by the cavities. The gettering efficiency of cavities increases with the decrease of Cu implantation doses and the increase of annealing temperatures. He+ ion implantation is found to be more suitable for cavity formation and impurity gettering than H+ ion implantation.

Total dose radiation effects of Au/PbZr0.52Ti0.48O3/YBa2Cu3O7-δ capacitors

PbZr0.52Ti0.48O3/YBa2Cu3O7−δ (PZT/YBCO) thin films have been fabricated on Y2O3 stabilized zirconate (YSZ) substrates by a pulsed excimer laser deposition (PLD) method. In order to investigate total dose radiation effects on the Au/PZT/YBCO ferroelectric capacitor, the capacitance–voltage (C–V) curves and the retained polarization property of the capacitor have been measured before and after γ-ray irradiation. The results showed that, with an increased total dose, the retained polarization and the dielectric constant decreased, but the coercive field drifted towards positive voltage direction. This is caused by charges trapped by defects in the PZT capacitor during irradiation.

Defect and strain in hydrogen and helium coimplanted single-crystal silicon

In this paper we studied the processes of blistering and exfoliation on the surface of crystal silicon, the evolution of defects/strains in the crystal silicon caused by hydrogen and helium coimplantation during annealing, and the formation of platelets and bubbles in the crystal. It is shown that H+ and He+ coimplantation produces a synergistic effect, which greatly decreases the total implantation dose, compared with either just H+ or He+ implantation. We also present the effect of coimplantation and analyse the different roles of H and He in the process of exfoliation during annealing. It seems that the essential role of hydrogen is to interact chemically with the defects in the silicon and create H-stabilized platelets, while the role of helium is to effuse into these platelets and exert a pressure on the inner surface of these platelets. The damage caused by coimplantation is lower than by hydrogen implantation (at the dose that exfoliation requires).

Structural and electrical characteristics of oxygen-implanted 6H-SiC

Silicon carbide is an important wide band gap semiconductor for high-temperature, high-voltage, high-power and high-frequency devices. Ion implantation is an important aspect for both fundamental r ...

Variation of strain/defects in H+-implanted single crystal silicon

Abstract Single crystal silicon samples were implanted with H + ions at an energy of 30 KeV, and a dose of 4×10 16 /cm 2 . These samples were annealed in the temperature range from 100°C to 500°C. Four-crystal X-ray diffractometer (FCXRD), cross-sectional transmission electron microscopy (XTEM), Rutherford backscattering spectroscopy and channeling (RBS/C) were used to characterize the distribution and magnitude of the strain and extended defects in the samples. Elastic recoil detection analysis (ERDA) was used to measure the redistribution of hydrogen in Si samples during annealing. Strain distributions in the samples were simulated from the rocking curves by computer. The results help to understand the evolution of the strain and defects during annealing in the high dose H + -implanted silicon samples.

Investigation of damage behaviour and isolation effect of n-type 6H-SiC by implantation of oxygen

Silicon carbide is an important wide-band-gap semiconductor for high temperature, high-voltage, high-power and high-frequency devices. Electrical isolation is an important aspect for device applications. In this report, oxygen ions, 70 keV with doses ranging from 5×1013 to 5×1015 cm-2, have been implanted into n-type 6H-SiC to investigate the possibility of forming a high-resistive layer. The damage behaviour and internal stress were checked by Rutherford backscattering spectroscopy and channelling, and an x-ray rocking curve, respectively. Atomic force microscope observations revealed that the surface morphology is quite sensitive to the implantation even at a dose of 1×1014 cm-2. After annealing in nitrogen at 1200 °C, no remarkable damage recovery could be seen if the deposit damage energy is over the critical value. Schottky structures of Au/SiC have been fabricated on the annealed samples and I-V curves of metal/SiC/InGeNi were measured at room temperature at both forward and reverse bias; the electrical isolation effect was observed at proper implantation dosages. The results indicated that there exists a dose window for electrical isolation.