InP基MOCVD及MBE外延生长HBT的制备与分析

设计并研制了用于光电集成(OEIC)的InP基异质结双极晶体管(HBT),介绍了工艺流程及器件结构。分别采用金属有机化学气相沉积(MOCVD)及分子束外延(MBE)生长的外延片,并在外延结构、工艺流程相同的条件下,对两种生长机制的HBT直流及高频参数进行和分析。结果表明,采用MOCVD生长的InP基HBT,直流增益为30倍,截止频率约为38GHz;MBE生长的HBT,直流增益达到100倍,截止频率约为40GHz。这表明,MBE生长的HBT外延层质量更高,在相同光刻条件下,所对应的HBT器件的性能更好。     

一种低暗电流高响度InGaAs/InP pin光电探测器

分析了InGaAs/InP pin光电探测器暗电流和响应度的影响因素,并对MOCVD外延工艺以及器件结构进行优化,从而提高器件响应度和降低暗电流。采用低压金属有机化学气相沉积设备(LP-MOCVD)成功制备了InGaAs/InP pin光电探测器,得到了高质量的晶体材料,InGaAs吸收层的背景浓度低于4×1014 cm-3。利用扩Zn工艺制作出感光区直径为70μm的平面光电探测器。测量结果显示,在反偏电压为5 V时,暗电流小于0.05 nA,电容约为0.4 pF。此外,在1 310 nm激光的辐照下,器件的响应度可达0.96 A/W以上。     

InGaAs/InP材料的Zn扩散技术

使用MOCVD反应室进行了InGaAs和InP材料上的Zn扩散工艺条件研究.通过控制扩散温度、扩散源浓度和扩散时间三个主要工艺参数,研究了InGaAs/InP材料的扩散系数和扩散规律,获得了优化的扩散条件.试验表明,该扩散工艺符合原子扩散规律,扩散现象可以用填隙-替位模型解释.样品经过快速退火过程,获得了极高的空穴浓度.InP的空穴浓度达到7.7×1018/cm3,而InGaAs材料达到7×1019/cm3.在优化的扩散条件下,Zn扩散的深度和浓度精确可控,材料的均匀性好,工艺重复性好,能够应用于光电探测器或其他器件.     

InP基长波长光发射OEIC材料的MOCVD生长

为了生长制作器件所需的外延片,采用低压金属有机物化学气相沉积方法在半绝缘InP衬底上生长了InP/InGaAs异质结双极晶体管(HBT)结构、1.55μm多量子阱激光二极管以及两者集成的光发射光电集成电路材料结构.激光器结构的生长温度为655℃,有源区为5个周期的InGaAsP/ InGaAsP多量子阱(阱区λ＝1.6μm,垒区λ＝1.28μm);HBT结构则采用550℃低温生长,其中基区采用Zn掺杂,掺杂浓度约为2×1019cm-3.对生长的各种结构分别进行了X射线双晶衍射,光致发光谱和二次离子质谱仪的测试,结果表明所生长的材料结构已满足制作器件的要求.     

MOCVD生长双波长发光二极管

根据白光照明和可变换波长的光通信中对单芯片双波长发光二极管(LED)要求,在分析了反向偏置隧道结性质的基础上,设计了用反向偏置隧道结连接两个有源区的单芯片双波长LED,用金属有机化学气相沉积技术(MOCVD)在GaAs衬底上一次外延生长了同时发射两种波长的LED,其包含一个AlGaInP量子阱有源区和一个GaInP量子阱有源区,两个有源区由隧道结连接;通过后工艺制备了双波长LED器件,在20mA电流注入下,可以同时发射626nm和639nm两种波长,光强是127mcd,正向电压是4.17V。与传统的单有源区LED进行对比表明,双波长LED有较强的光强;对比单有源区LED的2.08V正向电压,考虑到双波长LED包含隧道结和两个有源区,隧道结上的压降很小。     

MOCVD法生长二维范德华材料的研究进展

二维范德华材料凭借其优异的光学和电学特性,自被发现以来一直作为延续集成电路摩尔定律的重要基础电子材料而备受关注.通过机械剥离的方法得到高质量的二维材料进行实验室层面的研究工作已经不能满足现阶段的需要.采用金属有机化学气相沉积(MOCVD)技术可以得到高质量的大面积二维范德华材料,并具有生长层数和成核密度可控的优势.以过渡金属硫化物(TMDC)为例,分别从生长条件、金属有机源材料、衬底、催化剂等方面综述了采用MOCVD技术生长二维范德华材料的研究进展,同时讨论了二维材料的范德华异质结构的特性及应用.利用MOCVD技术优势可以推动二维范德华材料的大规模应用.最后总结了 MOCVD法生长二维范德华材料现阶段的优势与不足,并对其未来的发展进行了展望.     

MOCVD生长InGaAs/InP体材料研究

首先给出在InP衬底上利用MOCVD法生长InP、InGaAs的生长条件，而后分别给出了InP／InP的生长特性，InGaAs／InP的组份控制和生长特性及生长温度对InGaAs特性的影响。     

反应压力对MOCVD法沉积ZnO薄膜性质的影响

研究了反应压力对金属有机化学气相沉积(MOCVD)技术制备未掺杂ZnO薄膜的微观结构和光电特性影响.X射线衍射(XRD)和扫描电子镜(SEM)的研究结果表明,随着反应压力的降低,ZnO薄膜(002)择优峰的强度呈现相对减弱趋势,并且出现了较强的(110)峰;Hall测量表明,低的反应压力有助于提高薄膜电学特性.200 Pa时制备出的ZnO薄膜具有明显的"类金字塔"状绒面结构,电阻率为1.28×10-2 Ω·cm.实验中沉积的ZnO薄膜在600～2 600 nm内平均透过率超过80%,而短波长范围由于光散射作用,ZnO薄膜的垂直透过率有所下降.     

长波长、高灵敏度的InP／InGaAs谐振腔光电探测器

本文报道了一种能够实现高速、高灵敏度的InP基谐振腔增强型（RCE）光电探测器。它采用衬底入光方式，解决了在InP衬底上外延生长的InP/InGaAs介质膜分布布拉格反射镜（DBR）反射率低的问题，该探测器的吸收层厚度为0.2μm，在波长1.583μm处获得了80%的峰值量子效率，同时为了降低探测器的固有电容，利用质子注入技术使得器件的部分电极绝缘，实验结果表明质子注入不影响RCE光电探测器的量子效率。     

High performance InP JFETs grown by MOCVD using tertiarybutylphosphine

Indium phosphide channel junction field effect transistors were fabricated by metalorganic chemical vapor deposition using tertiarybulylphosphine (TBP) as the alternative source for phosphine. At growth temperatures of 600°C, InP with specular surface morphology and mobilities as high as 61000 cm₂/V s at 77Khas been achieved using trimethylindium and TBP. To improve device isolation, pinch-off characteristics, and output transconductance, we employ a high resistivity (1 × 10⁸ Ω-cm) semi-insulating InP buffer layer using ferrocene as the Fe-dopant. Devices with gate lengths of 1 urn exhibit very high extrinsic transconductance of 130 mS/mm, gate-drain breakdown voltage exceeding 20 V, maximum current density of >450 mA/mm with record high f_T and f_max of 15 GHz and 35 GHz, respectively. These results indicate: that InP JFETs are promising electronic devices for microwave power amplification, and that TBP is capable of device quality materials.     

Strain from modified interface compositions in InGaAs/InP superlattices

Thin strained regions have been inserted at the interfaces of lattice-matched InGaAs/lnP superlattices to assess growth conditions for tailoring of localized compositional changes and for studying As-P intermixing behavior during heterojunction growth. Also, precise growth rates of binary composition layers were determined from specially designed superlattices using strained layers of common anion compounds inserted periodically into InP and GaAs. Growth rates of fractional monolayers are found to be identical to thick layer growth rates. When thin InAs, GaAs, GaP, ALAs, or AIP layers were inserted at the InGaAs/lnP heterojunctions, the measured strain at either one or both interfaces was equal to the strain predicted from the growth rate x time product. Excess strain seen in some cases is due to a change in As-P intermixing and this component can be separated from the predicted strain. Insertion of Ga-compounds at the InP-grown-on-InGaAs interface causes interface roughening which degrades the superlattice. For all other compositions the thin, highly strained regions are not detrimental to the crystalline quality of the periodic structure.     

AlGaAs/GaAs quantum well infrared photodetector focal plane array based on MOCVD technology

128 × 128, 128 × 160 and 256 × 256 AlGaAs/ GaAs quantum well infrared photodetector (QWIP) focal plane arrays (FPA) as well as a large area test device are designed and fabricated. The device with n-doped back-illuminated AIGaAs/GaAs quantum structure is achieved by metal organic chemical vapor deposition (MOCVD) epitaxial growth and GaAs integrated circuit processing technology. The test device is valued by its dark current performance and Fourier transform infrared spectroscopy (FTIR) spectra at 77 K. Cut off wavelengths of 9 and 10.9 μm are realized by using different epitaxial structures. The blackbody detectivity DB* is as high as 2.6 × 109 cm· Hz1/2·W-1. The 128 × 128 FPA is flip-chip bonded on a CMOS readout integrated circuit with indium (In) bumps. The infrared thermal images of some targets under room temperature background have been successfully demonstrated at 80 K operating temperature. In addition, the methods to further improve the image quality are discussed.     

低压MOCVD生长ZnO单晶薄膜的制备与性质

利用 LP-MOCVD生长技术 ,采用 Zn(C2 H5) 2 作 Zn源和 CO2 作氧源 ,在 (0 0 0 2 )蓝宝石衬底上获得了沿 c轴取向高度一致的 Zn O单晶薄膜。通过对其吸收谱的曲线拟合 ,得到室温下 Zn O薄膜的光学带隙为 3 .2 45e V。在样品的室温光荧光谱 (PL)中观察到对应于带边发射的较强的发光峰 ,对样品中蓝带的产生原因进行了讨论     

Anomalous Lateral Zn Surface Diffusion in InP Caused by Zn-Contained Metallization

We report an anomalous Zn surface diffusion in InP during annealing of ohmic contact structures containing Zn. A Pd/Zn/Pd contact was used to demonstrate this phenomenon. Electrical properties of the contact were monitored to corroborate this anomalous surface diffusion. Cross-sectional scanning electron microscopy was also used to delineate the Zn diffusion front lines. It was found that the Zn surface lateral diffusion can extend ≥50 μm for samples annealed at 500°C or higher temperatures. Close attention should be paid to this anomalous lateral surface diffusion during fabrication of devices using Zn-contained ohmic contacts.     

Optical properties of InN films grown by MOCVD

By means of optical absorption, photolumines-cence (PL), Raman scattering and ellipsometry, optical properties of indium nitride (InN) films grown by metal organic chemical vapor deposition (MOCVD) are investigated. Through absorption and PL measurements, it is proven that the band gap of high quality InN is 0.68 eV, which agrees with the recently reported value, 0.7 eV. By analysis of the Raman scattering spectrum, the comparatively low background concentration of electron results in a smaller band gap value. The transition energy of wurtzite InN at critical point is determined by ellipsometric spectra. In addition, the complex refractive index of InN at energy ranging from 0.65 to 4.0 eV is obtained for the first time.     

Effects of S,Si, or Fe dopants on the diffusion of Zn in InP during MOCVD

Diffusion of Zn in InP during growth of InP epitaxial layers has been investigated in layer structures consisting of Zn-InP epilayers grown on S-InP and Fe-InP substrates, and on undoped InP epilayers. The layers were grown by metalorganic chemical vapour deposition (MOCVD) atT = 625° C andP = 75 Torr. Dopant diffusion profiles were measured by secondary ion mass spectrometry (SIMS). At sufficiently high Zn doping levels ([Zn] ≥8 × 10¹⁷ cm⁻³) diffusion into S-InP substrates took place, with accumulation of Zn in the substrate at a concentration similar to [S]. Diffusion into undoped InP epilayers produced a diffusion tail at low [Zn] levels, probably associated with interstitial Zn diffusion. For diffusion into Fe-InP, this low level diffusion produced a region of constant Zn concentration at [Zn] ≈ 3 × 10¹⁶ cm⁻³, due to kick-out of the original Fe species from substitutional sites. We also investigated diffusion out of (Zn, Si) codoped InP epilayers grown on Fe-InP substates. The SIMS profiles were characterised by a sharp decrease in [Zn] at the epilayer-substrate interface; the magnitude of this decrease corresponded to that of the Si donor level in the epilayer. For [Si] ≫ [Zn] in the epilayer no Zn diffusion was observed; Hall measurements indicated that the donor and acceptor species in those samples were electrically active. All these results are consistent with the presence of donor-acceptor interactions in InP, resulting in the formation of ionised donor-acceptor pairs which are immobile, and do not contribute to the diffusion process.