截止波长12μm的InAs0.04Sb0.96/GaAs的熔体外延生长及特性研究

用熔体外延(ME)法在半绝缘(100)GaAs衬底上成功生长出了截止波长为12 μm的InAs0.04Sb0.96外延层.傅立叶变换红外(FTIR)透射光谱揭示,InAsSb合金的禁带宽度被强烈变窄.通过分析InAs0.04Sb0.96外延层载流子浓度的温度依存性表明,其室温禁带宽度为0.105 5 eV,与透射光谱测得的数值很好地一致.通过测量12～300 K的吸收光谱,研究了InAs0.04Sb0.96/GaAs的禁带宽度的温度依存性.霍尔测量得出300 K下样品的电子迁移率为4.47×104 cm2/Vs,载流子浓度为8.77×1015 cm-3;77 K下电子迁移率为2.15×104 cm2/Vs,载流子浓度为1.57×1015 cm-3;245 K下的峰值迁移率为4.80×104 cm2/Vs.     

气态源分子束外延AlxGa1-xAs(x=0～1)材料中Si的掺杂行为研究

研究了Si在AlxGa1-xAs(0≤x≤1)中的掺杂行为.为比较Al組份对Si掺杂浓度的影响,在用气态源分子束外延生长(GSMBE)掺Si n型AlxGa1-xAs(0≤x≤1)的所有样品时,n型掺杂剂Si炉的温度恒定不变.用Hall效应测量外延层的自由载流子浓度和迁移率,用X射线双晶衍射迴摆曲线测量外延层的组份.测试结果表明,当AlxGa1-xAs中Al组份从0增至0.38时,Si的掺杂浓度从4×1018cm-3降至7.8×1016cm-3,电子迁移率从1900 cm2/Vs降至100 cm2/Vs.这与AlxGa1-xAs材料的Γ-X直接—间接带隙的转换点十分吻合.在AlxGa1-xAs全组份范囲内,自由载流子浓度隨Al组份从0至1呈“V”形变化,在X=0.38处呈最低点.在x>0.4之后,AlxGa1-xAs的电子迁移随Al组分的增加,一直维持较低值且波动幅度很小.     

N掺杂p型MgZnO薄膜的制备与性能研究

利用磁控溅射设备,Mg0.04Zn0.96O陶瓷靶材,以高纯的氮气与氩气混合气体作为溅射气体,在石英衬底上沉积获得了N掺杂p型Mg0.07Zn0.93O薄膜,薄膜的电阻率为21.47Ω·cm,载流子浓度为8.38×1016 cm-3,迁移率为3.45cm2/(V·s)。研究了该薄膜的结构与光学性能。实验结果显示,其拉曼光谱中出现了位于272和642cm-1左右与NO相关的振动模。低温光致发光光谱中,可以观察到位于3.201,3.384和3.469eV的3个发光峰,其中位于3.384eV的发光峰归因为导带电子到缺陷能级的复合发光,而位于3.469eV的发光峰归因为受主束缚激子(A0X)的辐射复合,这说明该N掺杂MgZnO薄膜的空穴载流子主要来自NO受主的贡献。     

MOCVD生长的GaN:Mg外延膜的光电性质

用MOCVD技术生长GaN:Mg外延膜,在550～950℃温度范围内,对样品进行热退火,并进行室温Hall、光致发光谱(PL)测试.Hall测试结果表明,850℃退火后空穴浓度达到8×1017 cm-3以上,电阻率降到0.8Ω·cm以下.室温PL谱有两个缺陷相关发光峰,位于2.8eV的蓝光峰(BL)以及3.27eV附近的紫外峰(UVL).蓝光峰对紫外峰的相对强度(BL/UVL)在550℃退火后升高,之后随着退火温度的升高(650～850℃)而下降,继续提高退火温度至950℃,BL/UVL急剧上升.空穴浓度先随着Mg掺杂浓度的增加而升高;但继续增加Mg掺杂浓度,空穴浓度反而下降.这些结果表明要实现空穴浓度达1018 cm-3,不仅要考虑H的钝化作用,还要考虑Mg受主的自补偿效应.     

MOCVD生长的GaN:Mg外延膜的光电性质

用MOCVD技术生长GaN:Mg外延膜,在550～950℃温度范围内,对样品进行热退火,并进行室温Hall、光致发光谱(PL)测试.Hall测试结果表明,850℃退火后空穴浓度达到8×1017 cm-3以上,电阻率降到0.8Ω·cm以下.室温PL谱有两个缺陷相关发光峰,位于2.8eV的蓝光峰(BL)以及3.27eV附近的紫外峰(UVL).蓝光峰对紫外峰的相对强度(BL/UVL)在550℃退火后升高,之后随着退火温度的升高(650～850℃)而下降,继续提高退火温度至950℃,BL/UVL急剧上升.空穴浓度先随着Mg掺杂浓度的增加而升高;但继续增加Mg掺杂浓度,空穴浓度反而下降.这些结果表明要实现空穴浓度达1018 cm-3,不仅要考虑H的钝化作用,还要考虑Mg受主的自补偿效应.     

低电阻率硼硫共掺杂金刚石薄膜的制备

利用微波气相沉积方法制备了低电阻率的n型硫掺杂和硼硫共掺杂金刚石薄膜.质子激发X射线荧光测试表明硼硫共掺杂方法能够提高硫在金刚石中的溶解度;扫描电镜和Raman光谱的分析结果表明掺杂金刚石薄膜的晶粒较完整,薄膜中存在较多的非金刚石碳相.Hall效应测试表明薄膜的导电类型为n型,电阻率为0 .0 2 4 6 Ω·cm,载流子浓度为2 .4 0×1 0 1 7cm- 3,Hall迁移率为1 0 3cm2 / (V·s) ;较低的电阻率是薄膜中存在sp2键和掺入的硫杂质等多种因素作用的结果     

用PLD方法制备Li掺杂的p型ZnMgO

在玻璃衬底上用PLD方法成功制备出具有高度(0002)取向性的、晶体质量较好的Li掺杂为0.4%的p型 Zn0.8Mg0.2O薄膜.衬底温度对薄膜的电学性能及结晶质量有重要影响,实验表明:在500℃时薄膜的电学性能最好,其载流子浓度为5.1×1018cm-3,电阻率为6.58Ω·cm,霍尔迁移率为0.189cm2/(V·s),且制备出的薄膜在可见光区具有90%的高透射率及在室温下光学禁带宽度3.625eV.     

用PLD方法制备Li掺杂的p型ZnMgO

在玻璃衬底上用PLD方法成功制备出具有高度(0002)取向性的、晶体质量较好的Li掺杂为0.4%的p型 Zn0.8Mg0.2O薄膜.衬底温度对薄膜的电学性能及结晶质量有重要影响,实验表明:在500℃时薄膜的电学性能最好,其载流子浓度为5.1×1018cm-3,电阻率为6.58Ω·cm,霍尔迁移率为0.189cm2/(V·s),且制备出的薄膜在可见光区具有90%的高透射率及在室温下光学禁带宽度3.625eV.     

自由电子激光对GaAs/AlGaAs异质结构材料电学性质的影响

自由电子激光(FEL)辐照样品前和辐照样品时,使用变温霍尔测量系统测试了这种n型调制掺杂GaAs/AlGaAs异质结构材料中准二维电子气(2DEG)的迁移率、电子浓度和电阻率。对比这两种情况下的结果可以发现:1)迁移率随温度升高而降低,光照使迁移率增大;2)电子浓度随温度变化关系相对较为复杂,但是平均而言,光照会使电子浓度减小;3)电阻率随温度升高而升高,光照使电阻率减小,但这种影响不明显。对这些现象给出了具体的分析。     

低电阻率硼硫共掺杂金刚石薄膜的制备

利用微波气相沉积方法制备了低电阻率的n型硫掺杂和硼硫共掺杂金刚石薄膜.质子激发X射线荧光测试表明硼硫共掺杂方法能够提高硫在金刚石中的溶解度;扫描电镜和Raman光谱的分析结果表明掺杂金刚石薄膜的晶粒较完整,薄膜中存在较多的非金刚石碳相.Hall效应测试表明薄膜的导电类型为n型,电阻率为0.0246·cm,载流子浓度为2.40×1017cm-3,Hall迁移率为103cm2/(V·s);较低的电阻率是薄膜中存在sp2键和掺入的硫杂质等多种因素作用的结果.     

Influence of laser recrystallization and hydrogen annealing on electrical characteristics of polysilicon

 Asenic ions are implanted with doses of 5×10~(11)—5×10~(15)/cm~2 into LPCVD polysilicon films on SiO_2 isolating substrate.The polysilicon films have been recrystallized with CW Ar~+ laser before implantation.Electrical measurements show that the resistivity is lowered and the mobility is increased significantly at low doping concentration(～10~(17)As~+/cm~3).Plasma hydrogen annealing is performed on laser-recrystallized samples.The electrical characteristics of plasma hydrogen annealed samples are close to that of single crystalline silicon.It is found that the resistivity decreases from 1.2 Ω.cm to 0.45 Ω.cm,the mobility rises from 62 cm~2/V.s to 271 cm~2/V.s,the electrical activation energy reduces from 0.03 eV to -0.007 eV and the trapping state density at the grain boundary drops from 3.7×10~(11)/cm~2 to 1.7×10~(11)/cm~2.Based on the existing theoretical models for conduction in polysilicon, a new formula for large grain polysilicon has been proposed,with the help of which,a good agreement between theory and experimental results is achieved within the doping concentration range from 10~(16)/cm~3 to 10~(20)/cm~3.     

掺杂浓度对多晶硅纳米薄膜应变系数的影响

为有效利用多晶硅纳米薄膜研制MEMS压阻器件,本文对LPCVD多晶硅纳米薄膜应变系数与掺硼浓度的关系进行了研究,并利用扫描电镜和X射线衍射实验分析了薄膜的结构特点.结果表明:在重掺杂情况下,纳米薄膜的应变系数明显大于相同掺杂浓度下单晶硅的应变系数,而且掺杂浓度在2.5×1020cm-3左右时,应变系数具有随掺杂浓度升高而增大的趋势.对这种实验结果依据隧道效应原理进行了理论解释,提出了多晶硅压阻特性的修正模型.     

P-N junction and Schottky barrier diode fabrication in laser recrystallized polysilicon on SiO2

P-N junction and Schottky barrier diodes have been fabricated in laser recrystallized polycrystalline silicon on SiO2. A repetitively Q-switched Nd³⁺:YAG laser was used to anneal polysilicon deposited by LPCVD on oxide thermally grown on     

Nd:YAG连续激光诱导下InP的Zn掺杂

Nd:YAG连续激光辐照在表面蒸有Zn薄膜的n-InP片上,用激光诱导的方法实现Zn在InP中掺杂。形成PN结。用电化学C-V方法和扫描电子显微镜对辐照后的样品进行分析研究,给出激光辐照功率、辐照时间等工艺参数对结深、浓度分布影响.在n-InP片表面得到受主浓度分布均匀、高掺杂（～1019cm-3）、浅结（～1μm）的P-InP。初步分析其掺杂机理是激光诱导下所形成的合金结过程。     

掺镁铌酸锂晶体抗光折变微观机理研究

研究了掺镁掺铁铌酸锂晶体的紫外，可见及红外光谱，首次发现当掺镁量超过通常所说的阈值（第一阀值）时，Fe^3 离子和部分Fe^2 离子的晶格占位由锂位变为铌位，但仍有部分Fe^2 离子留在锂位，晶体缺陷化学分析表明，继续增加掺镁量，占锂位的Fe^2 离子数瘵逐渐减小，当掺镁量达到另一个适当的值（第二阀值）时，全部Fe^2 都占铌位，晶体的抗光折变能力空前提高，这种现象称作双阀值效应。     

MOSFET's in electron-beam recrystallized PolySilicon

MOSFET's have been fabricated in polysilicon films recrystallized by scanned, cw electron-beam heating. The structure of the polysilicon is similar to the large-grain structure formed by cw laser recrystallization, and no significant differences were seen between the characteristics of transistors in material recrystallized by the two different types of heating.     

Laser recrystallized polysilicon on SiO2for high performance resistors

We demonstrate, for the first time, a technique for the fabrication of polysilicon resistors with excellent control and temperature characteristics: a standard deviation of 2.5 Ω and temperature variation of -5.6% from 25° to 125°C for 1.96 K Ω, 4.5 × 10¹⁴cm^-2Boron implanted polysilicon resistors. The technique is based on fabricating resistors in laser recrystallized polysilicon on SiO2. Resistor performance is compared to that of similar resistors fabricated in standard LPCVD polysilicon and in single crystal silicon.     

Retardation in the chemical-mechanical polish of the boron-dopedpolysilicon and silicon

This letter reports on the chemical-mechanical polishing (CMP) of boron-doped polysilicon and silicon. Successive polishing was carried out to investigate how the removal rate correlates to the boron concentration as a function of depth in the polysilicon and crystalline silicon. It is found that the removal of boron-doped samples is significantly retarded and strongly correlated with the doping concentration. To the author's knowledge, this work is the first report discussing the retardation effect of boron in the Si-CMP process. This effect is attributed to the activated dopant atoms which are conjectured to inhibit the hydrolysis reaction of Si-Si bonding in the alkaline aqueous solution. In our study, the retardation effect is evident for boron concentration higher than 5×10¹⁸ cm^-3. As a consequence, it may become an issue in the CMP process for those layers of selected or complemented doping     

ZnWO_4∶Cr~(3+)激光晶体的发光特性

研究了ZnWO_4Cr~(3+)激光晶体的发光特性,其中~4T_2能级分裂为13550、14205、14706cm~(-1)三个能级,荧光谱的斯托克斯漂移为3567cm~(-1),ZnWO4∶Cr~(3+)晶体的最强荧光峰位于912nm,最佳激发峰在622nm,掺杂浓度在0.01％时,荧光发射最强。用532nm激发时仍有很强的荧光发射。     

Modeling and optimization of monolithic polycrystalline silicon resistors

The processing parameters of monolithic polycrystalline silicon resistors are examined, and the effect of grain size on the sensitivity of polysilicon resistivity versus doping concentration is studied theoretically and experimentally. Because existing models for polysilicon do not accurately predict resistivity dependence on doping concentration as grain size increases above 600 Å, a modified trapping model for polysilicon with different grain sizes and under various applied biases is introduced. Good agreement between theory and experiments demonstrates that an increase in grain size from 230 to 1220 Å drastically reduces the sensitivity of polysilicon resistivity to doping levels by two orders of magnitude. Such an increase is achieved by modifications of the integrated-circuit processes. Design criteria for the optimization of monolithic polysilicon resistors have also been established based on resistivity control, thermal properties, and device geometry.