Effects of high-dose Ge ion implantation and post-implantation annealing on ZnO thin films

This paper reports that ion implantation to a dose of 1 ×10^17 ions/cm^2 was performed on c-axis-orientated ZnO thin films deposited on （0001） sapphire substrates by the sol-gel technique. After ion implantation, the as-implanted ZnO films were annealed in argon ambient at different temperatures from 600 - 900 ℃. The effects of ion implantation and post-implantation annealing on the structural and optical properties of the ZnO films were investigated by x-ray diffraction （XRD）, photoluminescence （PL）. It was found that the intensities of （002） peak and near band edge （NBE） exitonic ultraviolet emission increased with increasing annealing temperature from 600- 900 ℃. The defect related deep level emission （DLE） firstly increased with increasing annealing temperature from 600 - 750 ℃, and then decreased quickly with increasing annealing temperature. The recovery of the intensities of NBE and DLE occurs at ～850℃ and ～750℃ respectively. The relative PL intensity ratio of NBE to DLE showed that the quality of ZnO films increased continuously with increasing annealing temperature from 600 - 900 ℃.

Phase Transformation and Enhancing Electron Field Emission Properties in Microcrystalline Diamond Films Induced by Cu Ion Implantation and Rapid Annealing

Cu ion implantation and subsequent rapid annealing at 500℃ in N2 result in low surface resistivity of 1.611 ohm/sq with high mobility of 290 cm2 V-1S-1 for microcrystalline diamond （MCD） films. Its electrical field emission behavior can be turned on at Eo = 2.6 V/μm, attaining a current density of 19.5μA/cm2 at an applied field of 3.5 V/#m. Field emission scanning electron microscopy combined with Raman and x-ray photoelectron mi- croscopy reveal that the formation of Cu nanoparticles in MCD films can catalytically convert the less conducting disorder/a-C phases into graphitic phases and can provoke the formation of nanographite in the films, forming conduction channels for electron transportation.

Stress relaxation of Si/Si_(1-x)Ge_x/Si structure prepared by ion implantation and subsequent annealing process

The stress relaxation of 74Ge＋-implanted （100） silicon wafers was investigated. The implantation energy as a function of Si/Si1-xGex/Si struc-ture fluence and two kinds of thermal annealing were reported. The stress and stress relaxation after thermal annealing were calculated on the basis of Raman analysis, and were compared with those obtained from the calculation of virgin Si.

TiO_2 nanofilm growth by Ti ion implantation and thermal annealing in O_2 atmosphere

TiO2 nanofilms on surface of fused silica were fabricated by Ti ion implantation and subsequent thermal annealing in oxygen ambience. The silica glasses were implanted by 20 k V Ti ions to 1.5 × 1017ions/cm2 on an implanter of metal vapor vacuum arc(MEVVA) ion source. Effects of annealing parameters on formation,growth and phase transformation of the TiO2 nanofilms were studied in detail. Optical absorption spectroscopy,Raman scattering spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy measurements were done to figure out formation mechanism of the TiO2 nanofilms.The formation of TiO2 nanofilms was due to out-diffusion of the implanted Ti ions to the substrate surface,where they were oxidized into TiO2 nanoparticles. Formation, phase, and thickness of the TiO2 nanofilms can be well tailored by controlling annealing parameters.

Characteristics of La_0.7Sr_0.3MnO₃Films Modified by Aluminum Ions Implantation and Post-Implantation Annealing

The magnetron sputtered La0.7Sr0.3MnO3 films were implanted with different doses (5 ′ 1015 ions×cm?2 and 5 ′ 1016 ions×cm-2) of Al ions at different negative pulsed voltages (30 kV and 50 kV) by plasma based ion implantation and then annealed at 973 K for 1 h in air. The microstructure, surface morphologies, surface roughness, metal-insulator transition and room temperature emittance properties of the post-implantation annealed films were investigated and compared with those of the La0.7Sr0.3MnO3 film annealed at 973 K for 1 h in air. The results indicate that the post- implantation annealed films show single perovskite phase and obvious (100) preferred orientation growth. The Mn-O bond length, surface roughness and metal-insulator transition temperature (TMI) of the films can be effectively adjusted by changing implantation voltage or implantation dose of Al ions. However, the change of implantation parameters just has a small effect on room temperature emittance of the films. Compared with the annealed film, the post-implantation annealed films have shorter Mn-O bond length and lower room temperature emittance. The TMI of the films implanted at low voltage is lower than that of the annealed film, which mainly results from the degradation of oxidization during annealing process and the part displacement of Mn3+-O2+- Mn4+ double exchange channels by Al3+-O2?-Mn4+. The post-implanted annealed film implanted at 50 kV/5 ′ 1016 ions×cm-2 has a higher TMI than the annealed film, which is 247 K. The increase of TMI of the film implanted with high dose of Al ions at high voltage can be attributed to the improvement of microstructure.

Thermal annealing induced photocarrier radiometry enhancement for ion implanted silicon wafers

An experimental study on the photocarrier radiometry signals of As^＋ ion implanted silicon wafers before and after rapid thermal annealing is performed. The dependences of photocarrier radiometry amplitude on ion implantation dose （1×10^11-1×10^16/cm^2）, implantation energy （20-140 keV） and subsequent isochronical annealing temperature （500- 1100℃ are investigated. The results show that photocarrier radiometry signals are greatly enhanced for implanted samples annealed at high temperature, especially for those with a high implantation dose. The reduced surface recombination rate resulting from a high built-in electric field generated by annealing-activated impurities in the pn junction is believed to be responsible for the photocarrier radiometry signal enhancement. Photocarrier radiometry is contactless and can therefore be used as an effective in-line tool for the thermal annealing process monitoring of the ion-implanted wafers in semiconductor industries.

Effects of high temperature annealing and laser irradiation on activation rate of phosphorus

Thermal annealing and laser irradiation were used to study the activation rate of phosphorus in silicon after ion implantation.The activation rate refers to the ratio of activated impurity number to the total impurity number in the sample.After injecting phosphorus with the dose and energy(energy=55 keV,dose=3×10^(15) cm^(-2)),the samples were annealed at different temperatures,and laser irradiation experiments were performed after annealing.The experimental results showed that the activation rate of phosphorus was the highest at 850℃,and the highest activation rate was 67%.Upon femtosecond laser irradiation samples after thermal annealing,while keeping the crystalline silicon surface without damage,the activation rate was improved.When the energy-flux density of the femtosecond laser was 0.65 kJ/cm2,the activation rate was the highest,increasing from 67%to 74.81%.

High-Temperature Annealing Induced He Bubble Evolution in Low Energy He Ion Implanted 6H-SiC

Bubble evolution in low energy and high dose He-implanted 6H-SiC upon thermal annealing is studied. The （0001）-oriented 6H-SiC wafers are implanted with 15keV helium ions at a dose of 1×10^17 cm^-2 at room temperature. The samples with post-implantation are annealed at temperatures of 1073, 1173, 1273, and 1473K for 30rain. He bubbles in the wafers are examined via cross-sectional transmission electron microscopy （XTEM） analysis. The results present that nanoscale bubbles are almost homogeneously distributed in the damaged layer of the as-implanted sample, and no significant change is observed in the He-implanted sample after 1073 K annealing. Upon 1193 K annealing, almost full recrystallization of He-implantation-induced amorphization in 6H-SiC is observed. In addition, the diameters of He bubbles increase obviously. With continually increasing temperatures to 1273K and 1473 K, the diameters of He bubbles increase and the number density of lattice defects decreases. The growth of He bubbles after high temperature annealingabides by the Ostwald ripening mechanism. The mean diameter of He bubbles located at depths of 120-135 nm as a function of annealing temperature is fitted in terms of a thermal activated process which yields an activation energy of 1.914＋0.236eV.

H^+ Passivation of Poly-Si Solar CellsProcessed by Different Annealing Processes

The effects of different annealing processes on the photovoltaic (PV) properties and the spectral response as well as minority carrier lifetime in the bulk of unanalyzed PF5 ion implantation poly-Si solar cells were investigated. The different hydrogen passivation effects of defects in poly-Si induced by three heat treatment processes are reported. We used RTA-rapid thermal annealing, YAG pulse laser annealing and CTSA-classical three-step annealing for this study. The results show that cells processed by RTA (800°C, 4 sec) achieved the best PV properties and spectral response among all annealed samples. Under this precess condition, no or few defects were induced in bulk. While RTA (>-850°C for 4 sec), CTSA as well as YAG laser processes induced defects of different nature and concentration in the bulk of cells. It is further shown that hydrogen ion implantation significantly improved, the performances of poly-Si cells. It is able to efficiently remove the YAG laser induced defects in bulk. However, it cannot completely passivate the defects induced by CTSA and RTA processes.

Investigation of the inhibiting outdiffusion of erbium atoms to a silicon-on-insulator surface after annealing at high temperature

The annealing behaviour of 400 keV Er ions at a fluence of 2×10^15 cm^-2 implanted into silicon-on-insulator（SOI） samples is investigated by Rutherford backscattering spectrometry of 2.1 MeV He^2＋ ions with a multiple scattering model.It is found that the damage close to the SOI surface is almost removed after being annealed in O2 and N2 atmospheres,successively,at ℃,and that only a small number of the Er atoms segregated to the surface of the SOI sample,whereas a large number of Er atoms diffused to a deeper position because of the affinity of Er for oxygen.For the SOI sample co-implanted with Er and O ions,there is no evident outdiffusion of Er atoms to the SOI surface after being annealed in N2 atmosphere at ℃.

Ion implantation of semi-insulating InP materials

The methods for protecting InP surface against degradation during annealing,including encapsulant and encapsulant-free techniques;rapid thermal annealing of InP implanted layers;implanted ion species and some profiles of typical dopants,etc.,they are all the key techniques concerning ion implantation into semi-insulating InP,and have been reviewed synthetically as well.

THE DAMAGE MEASUREMENT OF ION- IMPLANTED COMPOUND SEMICONDUCTOR GaAs BY PIXE-CHANNELING TECHNIQUE

A combined PIXE-RBS channeling measurement system to examine Ⅲ-Ⅴ compound semiconductors has been established. Preliminary results on studying Si+ and Te+ implanted GaAs have been presented and discussed.

Optical and electronic properties of single modulation doped GaAs/AlGaAs V-grooved quantum wire modified by ion implantation

Single GaAs/Al0.5Ga0.5As V-grooved quantum wire modified by selective ion-implantation and rapid thermally annealing was investigated by spatially-resolved microphotoluminescence and magneto-resistance measurement. Spatially-resolved photoluminescence results indicate that the ion-implantation induced quantum well intermixing raises significantly the electron subband energies of the side quantum wells and vertical quantum wells, and more efficient accumulation of electrons in the quantum wires is achieved. Furthermore, the polarization properties of the photoluminescence from the quantum wires show large linear polarization degree up to 63%. Magneto- transport investigation on the ion implanted quantum wire samples presents the quasi-one dimensional intrinsic motion of electrons, which is important for the design and optimization of one dimensional electronic devices.

SI GaAS中S^+注入的电学特性

本文研究了经常规热退火和快速热退火后SIGaAs中S^+注入的电学特性.热退火后,GaAs中注入S^+的快扩散和再分布不决定于S^+或砷空位V_(AS)的扩散而决定于离子注入增强扩散.使用快速热退火方法能抑制注入S^+在GaAs中的增强扩散,明显减小S^+的再分布,可以获得适合于制造GaAs MESFET器件的薄有源层.

退火条件对注Mn GaAs结构的影响

通过离子注入在半绝缘GaAs衬底中掺引入Mn杂质,进行不同温度的退火后,在样品中形成了磁性MnAs粒子.利用原子力显微镜和磁力显微镜对样品的表面进行分析,发现退火条件会影响样品磁性粒子的分布.运用二次离子质谱仪测量了样品中Mn的深度分布,发现退火温度对样品中Mn的分布有很大影响.

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

The physical and electrical properties of BF2+ 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 BF2+ implanted samples at doses of 1×1015 and5×1015cm-2 after RTA.

Investigation on n-Type(-201)β-Ga_(2)O_(3)Ohmic Contact via Si Ion Implantation

Heavy doped n-typeβ-G_(2)O_(3)(HD-G_(2)O_(3))was obtained by employing Si ion implantation technology on unintentionally dopedβ-G_(2)O_(3)single crystal substrates.To repair the G_(2)O_(3)lattice damage and activate the Si after implantation,the implanted substrates were annealed at 950℃,1000℃,and 1100℃,respectively.High-resolution X-ray diffraction and high-resolution transmission electron microscopy show that the ion-implanted layer has high lattice quality after high-temperature annealing at 1000℃.The minimum specific contact resistance is 9.2×10^(-5)Ω·cm^(2),which is attributed to the titanium oxide that is formed at the Ti/G_(2)O_(3)interface via rapid thermal annealing at 480℃.Based on these results,the lateralˇ-G_(2)O_(3)diodes were prepared,and the diodes exhibit high forward current density and low specific on-resistance.

Planar nucleation and crystallization in the annealing process of ion implanted silicon

According to thermodynamic and kinetic theory,considering the variation of bulk free energy and superficial energy after nucleation as well as the migration of atoms,we study systematically the planar nucleation and crystallization that relate to two possible transition mechanisms in the annealing process of ion implanted S i：（1） liquid/solid transition：the critical nucleation work is equal to half the increased superficial energy and inversely proportional to the supercoolingΔT.Compared with bulk nucleation,the radius of the critical nucleus decreases by half,and the nucleation rate attains its maximum at T = Tm/2.（2） amorphous/crystalline transition：the atoms contained in the critical nucleus and situated on its surface,as well as critical nucleation work,are all directly proportional to the height of the nucleus,and the nucleation barrier is equal to half the superficial energy too.In addition,we take SiGe semiconductor as a specific example for calculation;a value of 0.03 eV/atom is obtained for the elastic strain energy,and a more reasonable result can be gotten after taking into account its effect on transition Finally,we reach the following conclusion as a result of the calculation：for the annealing of ion implanted Si,no matter what the transition method is—liquid or solid planar nucleation—the recrystallization process is actually carried out layer by layer on the crystal substrate,and the probability of forming a＂rod-like＂nucleus is much larger than that of a＂plate-like＂nucleus.

InAs/GaSb Ⅱ类超晶格材料的Si离子注入研究

Ⅱ类超晶格红外探测器一般通过台面结实现对红外辐射的探测,而通过离子注入实现横向PN结,一方面材料外延工艺简单,同时可以利用超晶格材料横向扩散长度远高于纵向的优势改善光生载流子的输运,且易于制作高密度平面型阵列。本文利用多种材料表征技术,研究了不同能量的Si离子注入以及退火前后对InAs/GaSb Ⅱ类超晶格材料性能的影响。研究通过Si离子注入,外延材料由P型变为N型,超晶格材料中产生了垂直方向的拉伸应变,晶格常数变大,且失配度随着注入能量的增大而增大,注入前失配度为-0.012%,当注入能量到200 keV时,失配度达到0.072%,超晶格部分弛豫,弛豫程度为14%,而在300℃ 60 s退火后,超晶格恢复完全应变状态,且晶格常数变小,这种张应变是退火引起的Ga-In相互扩散以及Si替位导致的晶格收缩而造成的。

GaAs亚微米自对准工艺技术研究

总结了在５０ｍｍＧａＡｓ圆片上实现自对准介质膜隔离等平面工艺技术的研究，着重描述了离子注入、自对准亚微米难熔栅制备、钝化介质膜生长、干法刻蚀、电阻和电容制备等关键工艺的研究结果。这套工艺的均匀性、重复性好，在５０ｍｍＧａＡｓ圆片上获得了满意的成品率。采用这套工艺已成功地研制出多种性能良好的ＧａＡｓＩＣ和ＧａＡｓ功率ＭＥＳＦＥＴ，证明国家自然科学基金委员会这一重大课题的选择对发展我国ＧａＡｓＩＣ确实具有重大意义。