半导体发光器件的一种新的端面保护和减反射介质膜

人们早已开始研究半导体发光器件的端面保护和减反射膜,但直至现在成功地用来做保护和减反射膜的只有O、SiO、Al_2O_3和SiN等几种电介质膜。此外,氮化铝(AlN)膜的制备和它的性质及其应用也有所研究。本文报道溅射AlN膜用来做半导体发光器件端面保护和减反射膜的实验研究结果,发现溅射AlN膜将是半导体光电器件的一种新的具有良好性     

具有AlN膜的半导体激光器的实验研究

本文报道使用溅射AlN膜做半导体激光器端面反射膜和表面纯化膜的实验研究结果。测量结果表明,使用溅射AlN膜做表面纯化膜的半导体激光器性能良好。     

国外简讯

AlN/Si声表面波器件 SAW器件的一个新的发展分支是与半导体相结合的集成化技术。在Si片上溅射ZnO薄膜以激励和传播SAW已进行过大量的工作。AlN也是一种适用于SAW器件的压电薄膜材料,而且它的化学稳定性、机械强度、声速和机电耦合系数可能还优于ZnO膜,这就使得AlN膜有可能用作单片SAW器件以取代ZnO。 AlN膜的生长方法较多,如CVD法、RF溅射等。这些方法都要求基片温度在1000℃以上。在较低温度下在玻璃和兰宝石基片成功地沉积AlN膜,只是在最近才用反应溅射实现的。美国珀杜大学电工系L.G.Pearce等人用有磁控阴极的MRC-8620型RF平面溅射系统沉积了高度取向的AlN膜,并制成了几种新型的AlN/Si SAW器件。     

基于AlN膜钝化层的高功率垂直腔面发射激光器

高功率垂直腔面发射半导体激光器(VCSEL)内部的自生热是影响器件功能的重要因素,为改善器件的散热性能,采用AlN膜做钝化层研制了基于AlN膜钝化层的980 nm高功率VCSEL器件。对高功率VCSEL进行模拟仿真与理论分析表明,采用AlN膜钝化层可以改善器件内部的温度分布,降低器件的热阻,提高器件的散热能力;采用相同的外延片与工艺实验制备了出光孔径同为200μm的AlN膜钝化层和传统的SiO2膜钝化层的高功率VCSEL器件;对两种不同的钝化层的器件性能进行了实验对比测试,结果表明AlN膜钝化层的高功率VCSEL器件室温下的最大输出功率可达470 mW,比同温度下SiO2膜钝化层的高功率VCSEL器件的最大输出功率高140 mW。AlN膜钝化层的高功率VCSEL在外界温度80℃时,仍能正常激射,具有良好的温度适应性与光电性能。     

溅射AlN技术对GaN基LED性能的影响

研究了在图形蓝宝石衬底(PSS)上利用磁控溅射制备AlN薄膜的相关技术,随后通过采用金属有机化学气相沉积(MOCVD)在相关AlN薄膜上生了长GaN基LED.通过一系列对比实验,分析了AlN薄膜的制备条件对GaN外延层晶体质量的影响,研究了AlN薄膜溅射前N2预处理功率和溅射后热处理温度对GaN基LED性能的作用机制.实验结果表明:AlN薄膜厚度的增加,导致GaN缓冲层成核密度逐渐升高和GaN外延膜螺位错密度降低刃位错密度升高;N2处理功率的提升会加剧衬底表面晶格损伤,在GaN外延膜引入更多的螺位错;AlN热处理温度的升高粗化了表面并提高了GaN成核密度,使得GaN外延膜螺位错密度降低刃位错密度升高;而这些GaN外延膜位错密度的变化又进一步影响到LED的光电特性.     

超宽禁带AlN材料及其器件应用的现状和发展趋势

作为一种Ⅲ-Ⅴ族化合物半导体材料,AlN不仅具有超宽直接带隙(6.2 eV)、高热导率、高电阻率、高击穿场强、优异的压电性能和良好的光学性能,而且AlN晶体还与其他Ⅲ-N材料具有非常接近的晶格常数和热膨胀系数。这些特点决定了AlN在GaN外延、紫外光源、辐射探测器、微波毫米波器件、光电器件、电力电子器件以及声表面波器件等领域具有广阔的应用前景。介绍了AlN材料在功率器件、深紫外LED、激光器、传感器以及滤波器等领域的应用现状,并对AlN材料及其应用的未来发展趋势进行了分析和展望。     

红外接收用PIN硅光电探测器研究

PN二极管是一种常用的光电探测器,其中PIN光电二极管因其体积小、噪声低、响应速度快、光谱响应性能好等特点已作为一个标准件广泛应用于红外遥控接收领域。文章基于半导体材料的光吸收特性和光电效率转换原理,同时结合减反射膜理论,对PIN光电二极管进行研究,通过衬底材料的合理选择,对减反射膜折射率及厚度进行对比实验,验证了SiN膜层较SiO2膜有着更为良好的减反射效果,可以有效提升光敏器件的光电转换效率,同条件下器件的光生电流得到提升,为今后光电器件的生产、开发应用提供了参考。     

碳化硅封装高功率半导体激光器散热性能研究

为研究基于碳化硅(SiC)陶瓷封装的高功率半导体激光器的散热性能,将其与常用的氮化铝(AlN)陶瓷进行对比,使用基于结构函数法的热阻仪分别测量SiC和AlN封装F-mount器件的热阻值,得到SiC器件的总热阻约为3.0℃·W~(-1),AlN的约为3.4℃·W~(-1),SiC器件的实测热阻值比AlN器件低14.7%,实验结果表明SiC过渡热沉具有较好的散热性能。实验进一步测试了两种过渡热沉封装器件的输出性能,在16A连续电流注入时,915nm波段的SiC器件单管输出功率为15.9 W,AlN为15 W,测试结果显示SiC封装的器件具有更高的功率输出水平。     

Au/CdTe+ZnS/HgCdTe双层介质膜MIS器件的制备及研究

通过介质膜ZnS、CdTe薄膜材料的Ar+束溅射沉积研究,结合HgCdTe器件工艺,成功制备了以ZnS、CdTe双层介质膜为绝缘层的HgCdTeMIS器件;通过对器件的C-V特性实验分析,获得了CdTe/HgCdTe界面电学特性参数.实验表明溅射沉积介质膜CdTe+ZnS对HgCdTe的表面钝化已经可以满足HgCdTe红外焦平面器件表面钝化的各项要求.     

Au／CdTe＋ZnS／HgCdTe双层介质膜MIS器件的制备及研究

通过介质膜ZnS、CdTe薄膜材料的Ar^ 束溅射沉积研究,结合HgCdTe器件工艺,成功制备了以ZnS、CdTe双层介质膜为绝缘层的HgCdTe MIS器件;通过对器件的C－V特性实验分析,获得了CdTe/HgCdTe界面电学特性参数。实验表明：溅射沉积介质膜CdTe ZnS对HgCdTe的表面钝化已经可以满足HgCdTe红外焦麦面器件表面钝化的各项要求。     

X波段FBAR用AlN薄膜制备研究

采用中频磁控溅射法,在硅基上制备了X波段薄膜体声波谐振器(FBAR)滤波器用AlN压电薄膜。对AlN薄膜进行了分析表征,结果表明,AlN压电薄膜具有良好的(002)面择优取向,摇摆曲线半峰宽为2.21°,膜厚均匀性优于0.5%,薄膜应力为-5.02 MPa,应力可在张应力和压应力间进行调节。将该AlN薄膜制备工艺应用于FBAR器件的制作,研制出X波段FBAR器件,谐振频率为9.09 GHz,插入损耗为-0.38 dB。     

靶基距对反应溅射AlN薄膜微结构和性能的影响

采用射频(RF)磁控反应溅射法在Si基底上制备了氮化铝(AlN)薄膜,利用X射线衍射(XRD)、傅立叶红外光谱(FTIR)、扫描电子显微镜(SEM)和纳米力学测试系统研究靶基距对AlN薄膜取向性、微结构、形貌和力学性能的影响。结果表明,靶基距较大时,形成的AlN薄膜为非晶态,薄膜表面较疏松;随着靶基距的减少,AlN薄膜变为多晶态,且具有(100)择优取向;随着靶基距的进一步减少,薄膜结晶质量变好,晶粒变大,薄膜变得更致密,择优取向也由(100)逐渐向(002)转变;靶基距较小时,AlN压电薄膜与基底结合得更牢固,而压电薄膜与基底结合的紧密程度对多层膜声表面波(SAW)器件性能优劣的影响至关重要。     

Structural Properties of AlN Grown on Sapphire at Plasma Self-Heating Conditions Using Reactive Magnetron Sputter Deposition

Aluminum nitride (AlN) films were grown on sapphire by reactive magnetron sputter deposition in N₂ discharges at plasma self-heating conditions. The growth temperature was as low as 94°C. The structural properties resulting from different substrate biases and growth pressures were investigated by atomic force microscopy, x-ray diffraction (XRD) measurements, and transmission electron microscopy (TEM). At 20 mTorr of N₂ with most sputtered species thermalized, films exhibited both AlN (0002) and (10[`1] 1) (10\overline{1} 1) XRD peaks, with the AlN (0002) intensity initially increasing with ion energy above 15 eV, showing enhanced film quality with an optimum of 25 eV. At a lower growth pressure of 5 mTorr with energetic sputtered species, the AlN (10[`1] 1) (10\overline{1} 1) peak disappeared and the crystallinity of AlN improved, exhibiting relaxed epitaxial AlN. The measured lattice parameter was 0.4975 nm, which was 0.10% smaller than that of bulk. The epitaxial relationship of a single-crystal AlN film was confirmed by pole figure and cross-sectional TEM. These results demonstrate that control of ion energy and energy of the sputter-deposited species is critical for film deposition at low temperature.     

Oxygen Nitrogen Mixture Effect on Aluminum Nitride Synthesis by Reactive Ion Plasma Deposition

In the work we investigate synthesis of aluminum nitride films using reactive ion plasma deposition in oxygen/nitrogen gas mixture for application as optical elements for power semiconductor lasers. The experimental refractive index of synthesized AlNO films is dependent on oxygen composition and is decreasing in diapason from 1.76 to 2.035 at elevation of the oxygen fraction.It is shown that the AlN films synthesized by pure nitrogen plasma are polycrystalline and textured. The oxygen presence in discharging gas results to growth of amorphous phase of the AlNO film.     

Theoretical investigation of the electronic and structural properties of AlN thin films

Studying the electronic and structural properties of AlN thin films is an important problem because such films are widely used as a buffer layer when growing GaN-based semiconductor heterostructures on Si substrates. In this paper, we carry out a theoretical investigation of the properties of an Al-terminated AlN(0001) surface in the framework of the density functional theory. Ab initio calculations allow us to analyze the effect of the in-plane lattice strain on the energy of this surface. It is shown that compressive strain causes a decrease in the AlN(0001) surface energy, while tensile strain leads to its increase. Knowing the surface energy values allows us to evaluate the stress of the surface under investigation. In addition, the curvature of the AlN surface is calculated for various AlN film thicknesses in the case of free growth. The obtained values of the surface curvature are in close agreement with the known experimental results.     

Investigation of AlN Thin Films as Buried Insulator in SOI Structure

Self-heating effects in silicon-on-insulator (SOI) devices limit the applicability of SOI materials in electronics in cases where high power dissipation is expected. AlN film as a potential candidate for buried insulator material in SOI-structures is investigated. Ion-beam-enhanced deposition (IBED) is used to manufacture large area AlN films. SIMS measurements indicate the formation of AlN films. The characterization of the films reveals that the quality of the films strongly depends on the evaporation rate of Al. For the film with high quality deposited at 0.05nm/s, it has higher component of N, excellent dielectric property and a smoother surface with roughness RMS value of 0.13nm, and can be bonded directly at room temperature by the smart-cut process. SOI structure with the AlN film as buried insulator has formed successfully for the first time, which is confirmed by XTEM micrograph.     

AlN薄膜制备技术研究

采用磁控溅射法制备了AlN薄膜并研究了射频(RF)等离子清洗对AlN薄膜结晶取向度的影响,实验表明,RF等离子清洗基片3min后AlN薄膜c轴取向摇摆曲线半峰宽达到1.3°;通过Mo薄膜衬底对AlN薄膜结晶取向度的影响发现,取向度好的Mo薄膜衬底有利于c轴取向AlN薄膜的生长;Ar气体流量对AlN薄膜应力的影响使AlN薄膜应力从-390(压应力)~73 MPa(张应力)可调。     

氮化铝粉体制备技术的研究进展

氮化铝(AlN)因具备优良的理化性能,目前已被广泛应用于微电子及半导体器件的基板和封装领域中,同时在功率器件、深紫外LED及半导体衬底方面也具有广阔发展前景。AlN粉体作为AlN产品的主要原料是决定其性能的关键因素。在对AlN的结构与性能综合分析基础上,系统介绍了当前AlN粉体制备技术的研究进展和应用现状,同时对各制备工艺的特点进行了分析探讨。指出在微米AlN粉体制备方面,碳热还原法和直接氮化法仍具有明显优势,而化学气相沉积法和等离子体法则在纳米AlN粉体制备方面具有良好的应用前景。获得更高纯度、粒度可控、形貌均匀分散的粉体是AlN制备技术的研究方向。