Radiation hardness improvement of separation-by-implantation-of-oxygen/silicon-on-insulator material by nitrogen ion implantation

In our work, nitrogen ions were implanted into separation-by-implantation-of-oxygen (SIMOX) wafers to improve the radiation hardness of the SIMOX material. The experiments of secondary ion mass spectroscopy (SIMS) analysis showed that some nitrogen ions were distributed in the buried oxide layers and some others were collected at the Si/SiO₂ interface after annealing. The results of electron paramagnetic resonance (EPR) suggested the density of the defects in the nitrided samples changed with different nitrogen ion implantation energies. Semiconductor-insulator-semiconductor (SIS) capacitors were made on the materials, and capacitance-voltage (C-V) measurements were carried out to confirm the results. The super total dose radiation tolerance of the materials was verified by the small increase of the drain leakage current of the metal-oxide-semiconductor field effect transistor with n-channel (NMOSFETs) fabricated on the materials before and after total dose irradiation. The optimum implantation energy was also determined.     

低能离子注入的应用

集成电路的发展要求制备出超浅结或超薄有源层，以满足器件高密度和高速度的要求，低能离子注入是形成浅结的最有效手段，本文介绍了低能离子注入硅和ＧａＡｓ衬底中形成０．１ｕｍ以下的硅超浅结和ＧａＡｓ超薄有源层，以及它们在一些器件上应用的结果。     

Effect of copper ions implantation on corrosion behavior of zircaloy-4 in 1 M H2SO4

In order to study the effect of copper ion implantation on the aqueous corrosion behavior, samples of zircaloy-4 were implanted with copper ions with fluences ranging from 1 × 10¹⁶ to 1 × 10¹⁷ ions/cm², using a metal vapor vacuum arc source (MEVVA) operated at an extraction voltage of 40 kV. The valence states and depth distributions of elements in the surface layer of the samples were analyzed by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), respectively. Glancing angle X-ray diffraction (GAXRD) was employed to examine the phase transformation due to the copper ion implantation. The potentiodynamic polarization technique was employed to evaluate the aqueous corrosion resistance of implanted zircaloy-4 in a 1 M H₂SO₄ solution. It was found that a significant improvement was achieved in the aqueous corrosion resistance of zircaloy-4 implanted with copper ions when the fluence is smaller than 5 × 10¹⁶ ions/cm². The corrosion resistance of implanted samples declined with increasing the fluence. Finally, the mechanism of the corrosion behavior of copper-implanted zircaloy-4 was discussed.     

Doping of 3C-SiC by implantation of nitrogen at high temperatures

Doping profiles and electrical properties are investigated on SiC samples doped with single energy implants from nitrogen. The profiles are analyzed using Pearson distributions for different implantation energies and temperatures. Implantations are performed for temperatures up to 1200°C. Diffusion during high temperature implantation is investigated and the diffusion coefficients measured range from 1.09 × 10⁻¹⁵ to 1.53 × 10⁻¹⁴cm²/s depending on temperature. The activation energy for implantation enhanced diffusion is estimated to be 0.91 eV. A comparison is made with diffusion during annealing. The activated dopants from high temperature implantation are investigated by the Hall probe method, showing that activation and mobility increase with temperature.     

Homogeneity analysis of ion-implanted resonant tunnelling diodes for applications in digital logic circuits

A planar process for molecular beam epitaxy grown resonant tunnelling diodes (RTDs) in the GaAs/AlAs material system is presented and analysed with respect to the homogeneity of the diodes. The results can be correlated with a parameter sensitivity study based on quantum mechanical transport simulations. The homogeneity analysis reveals that our concept provides sufficient precision to fabricate RTDs suitable for application in robust digital logic circuits.     

Optical and electrical properties of AlGaN films implanted with Mn,Co, or Cr

The electrical and optical properties of undoped n-AlGaN films with Al mole fraction close to x=0.4 were studied before and after implantation of 3×10¹⁶ cm⁻² 250-keV Mn, Co, and Cr ions. The electrical properties of the virgin samples are shown to be dominated by deep donors with the level near E_c-0.25 eV and concentration of about 2×10¹⁸ cm⁻³. The microcathodoluminescence (MCL) spectra of the virgin samples were dominated by two strong defect bands at 2.5 eV and 3.7 eV. After implantation, the resistivity of the implanted films increased but could not be accurately measured because of the shunting influence of the unimplanted portions of the films. Their resistivity was increased by more than an order of magnitude compared to the virgin samples because of the compensation by defects coming from the implanted layer during the post-implantation annealing. The absorption and luminescence spectra of the implanted samples were dominated by two strong bands near 2 eV and 3.5 eV. The latter are attributed to the electron transitions from the Mn, Co, or Cr acceptors to the conduction band.     

低能离子注入引起的植物种子微结构的变化

以植物干种子芸豆和花生为生物体材料，采用正电子湮没技术（PAT）测定了该两类生物样品的正电子湮没寿命谱（PAL）。测量结果表明，在芸豆和花生生物体内存在着大量微小的孔洞，孔洞的直径分别为0．48nm和0．7nm。植物种子的这类特殊的微孔结构是低能离子注入生物效应机理的基础。对注入200keV低能V离子的花生样品也测量了它的PAL谱，并与未经离子注入的花生样品的PAL谱作了比较。     

1-3μm硼注入碲镉汞光伏器件的C-V禾G-V特性研究

利用自制的阻抗测量系统研究了碲镉汞光伏器件的Ｃ－Ｖ和Ｇ－Ｖ特性．实验结果表明：器件有着复杂的内在结构，可能是ｎｐｎ＋三层结构中的ｐｎ＋结起主导作用．此外，所有器件的Ｃ－Ｖ特性都表现出相似的反常特性，室温下这种效应比低温下更为明显．     

Solid state effects during deuterium implantation into copper and titanium

Results of neutron counting experiments during deuterium implantation into titanium and copper are reported. Models for neutron yield have been developed by taking into account different solid state effects like energy degradation of incident ions, energy dependent d-d fusion cross section and diffusion of implanted deuterium possibly influenced by surface desorption and formation of metal deuterides. The asymptotic time dependence of the neutron yield during implantation has been compared with the experimental results. Using these results, solid state processes that might occur during deuterium implantation into these metals are inferred.     

FLUORINE BEHAVIOR IN BF_2~+ IMPLANTED POLYSILICON FILMS SUBJECTED TO RAPID THERMAL ANNEALING

The physical and electrical properties of BF_2~+ implanted polysilicon films subjectedto rapid thermal annealing(RTA)are presented.It is found that the out diffusion of F and itssegregation at polysilicon/silicon oxide interface during RTA are the major causes of F anomalousmigration.Fluorine bubbles were observed in BF_2~+ implanted samples at doses of 1×10~(15) and5×10~(15)cm~(-2) after RTA.