Solar‑Driven Sustainability:Ⅲ–ⅤSemiconductor for Green Energy Production Technologies

Long-term societal prosperity depends on addressing the world’s energy and environmental problems,and photocatalysis has emerged as a viable remedy.Improving the efficiency of photocatalytic processes is fundamentally achieved by optimizing the effective utilization of solar energy and enhancing the efficient separation of photogenerated charges.It has been demonstrated that the fabrication ofⅢ–Ⅴsemiconductor-based photocatalysts is effective in increasing solar light absorption,long-term stability,large-scale production and promoting charge transfer.This focused review explores on the current developments inⅢ–Ⅴsemiconductor materials for solar-powered photocatalytic systems.The review explores on various subjects,including the advancement ofⅢ–Ⅴsemiconductors,photocatalytic mechanisms,and their uses in H2 conversion,CO_(2)reduction,environmental remediation,and photocatalytic oxidation and reduction reactions.In order to design heterostructures,the review delves into basic concepts including solar light absorption and effective charge separation.It also highlights significant advancements in green energy systems for water splitting,emphasizing the significance of establishing eco-friendly systems for CO_(2)reduction and hydrogen production.The main purpose is to produce hydrogen through sustainable and ecologically friendly energy conversion.The review intends to foster the development of greener and more sustainable energy source by encouraging researchers and developers to focus on practical applications and advancements in solar-powered photocatalysis.

Thermodynamic analysis of growth of ternary Ⅲ-Ⅴ semiconductor materials by molecular-beam epitaxy

Thermodynamic models for molecular-beam epitaxy（MBE） growth of ternary Ⅲ-Ⅴ semiconductor materials are proposed.These models are in agreement with our experimental materials InGaP/GaAs and InGaAs/InP,and reported GaAsP/GaAs and InAsP/InP in thermodynamic growth.The lattice strain energy △G and thermal decomposition sensitive to growth temperature are demonstrated in the models simultaneously.△G is the function of the alloy composition,which is affected by flux ratio and growth temperature directly.The calculation results reveal that flux ratio and growth temperature mainly influence the growth process.Thermodynamic model of quaternary InGaAsP/GaAs semiconductor material is discussed also.

Luminescence Characteristics of Yb^(3+) and Er^(3+) in Ⅲ-Ⅴ Semiconductors

The sharp luminescent peaks in Yb and Er-implanted InP,SI-InP,GaAs,and n-GaAs were observed at 77K.The peaks at 1.0 and 1.5μm come from(4f)~2F_(5/2)→~2F_(7/2)of Yb^(3+)and ~4I_(13/2)→~4I_(15/2)of Er^(3+), respectively.The optimum luminescent intensities can be obtained from Yb-implanted and Er-implanted sam- ples which were annealed at 800 and 750℃,respectively.A ccording to the analyses of PL and the rocking curve of X-ray double crystal diffraction,the best crystal structure of implanted InP layer has been obtained by an- nealing at 850℃.The interaction between Yb^(3+)and Er^(3+)in the SI-InP has been investigated for the first time. The quenching effect of Yb^(3+)and Er^(3+)with each other has been observed when the doses of Yb and Er-im- planted SI-InP are equal.

GaAsBi半导体材料的制备及应用研究进展

稀铋Ⅲ-Ⅴ半导体材料在电子和光电子领域具有广泛的应用前景,其制备方法主要有分子束外延法(MBE)和金属有机物气相外延法(MOVPE)。本文聚焦于具有较大带隙收缩、温度不敏感以及强自旋轨道分裂等特殊物理特性的GaAs_(x)Bi_(1-x)半导体材料,对其制备方法和研究进展进行了综述。研究人员对GaAsBi材料的研究主要集中在薄膜、多量子阱、纳米线和量子点材料的制备。在薄膜材料方面,侧重于研究制备工艺条件对GaAsBi薄膜的影响,例如低衬底温度、低生长速率和非常规的Ⅴ/Ⅲ束流比;在多量子阱材料方面,采用双衬底温度技术有效减少Bi偏析问题;对于纳米线和量子点材料,金属Bi作为表面活性剂可以改善材料的形貌和光学性能。然而,目前在该材料研究和应用方面仍存在挑战,如薄膜材料的结晶质量恶化和金属Bi分凝团聚,以及量子点材料中Bi的均匀性和形成机制的争议。解决这些问题对于提高GaAs_(x)Bi_(1-x)半导体材料的质量和促进器件发展具有重要意义。

Latest advances in high-performance light sources and optical amplifiers on silicon

Efficient light generation and amplification has long been missing on the silicon platform due to its well-known indirect bandgap nature.Driven by the size,weight,power and cost(SWaP-C)requirements,the desire to fully realize integrated silicon electronic and photonic integrated circuits has greatly pushed the effort of realizing high performance on-chip lasers and amplifiers moving forward.Several approaches have been proposed and demonstrated to address this issue.In this paper,a brief overview of recent progress of the high-performance lasers and amplifiers on Si based on different technology is presented.Representative device demonstrations,including ultra-narrow linewidthⅢ-Ⅴ/Si lasers,fully integratedⅢ-Ⅴ/Si/Si3N4 lasers,high-channel count mode locked quantum dot(QD)lasers,and high gain QD amplifiers will be covered.

Growth of Ⅲ-Ⅴ semiconductor nanowires and their heterostructures

In this paper, we present a review about recent progress on the growth of III-V semiconductor homo- and heterostructured nanowires. We will first deliver a general discussion on the crystal structure and the conventional growth mechanism of one dimensional nanowires. Then we provide a review about most widely used growth techniques, sample preparation and the cutting edge characterization techniques including advanced electron microscopy, in situ electron diffraction, micro-Raman spectroscopy, and atom probe tomography. In the end, the growth of different heteostructured III-V semiconductor nanowires will be reviewed. We will focus on the morphology dependence, temperature influence, and III/V flux ratio dependent growth. The perspective and an outlook of this field is discussed in order to foresee the future of the fundamental research and application of these one dimensional nanostructures.

Epitaxial Techniques for Compound Semiconductor Growth:from LPE to MOVPE

The epitaxial techniques are the most important processes in the production of semiconductor materials and optoelectronic devices. Liquid phase epitaxy (LPE) and metal organic vapor phase epitaxy (MOVPE) particularly have many applications.The process characteristics and crystalline properties of both LPE and MOVPE techniques were introduced briefly, the compositional space suitable for LPE and MOVPE growth was discussed from the view point of thermodynamic equilibrium. The analysis and comparison show that on the one hand LPE and MOVPE have some advantages and characteristics in common; on the other hand, they may overcome each other′s weaknesses and deficiencies by offering their own special features.

>35%5-junction space solar cells based on the direct bonding technique

Multijunction solar cells are the highest efficiency photovoltaic devices yet demonstrated for both space and terrestrial applications.In recent years five-junction cells based on the direct semiconductor bonding technique(SBT),demonstrates space efficiencies>35%and presents application potentials.In this paper,the major challenges for fabricating SBT 5J cells and their appropriate strategies involving structure tunning,band engineering and material tailoring are stated,and 4-cm235.4%(AM0,one sun)5J SBT cells are presented.Further efforts on detailed optical managements are required to improve the current generating and matching in subcells,to achieve efficiencies 36%-37%,or above.

What has been measured by reflection magnetic circular dichroism in Ga_(1-x)Mn_xAs/GaAs structures?

An explicit expression of reflection magnetic circular dichroism （RMCD） has been derived, taking into account the interference effect that arises from multiple internal reflections in an air/Ga1-xMnxAs/GaAs dielectric layered system. It unambiguously shows that the RMCD signal is composed by three terms. In addition to the conventional term, which is sufficient in the absence of interference, an oscillatory term is required. Both of them are related to the imaginary part εxy of the off-diagonal element of the dielectric tensor. One also becomes aware that in this case RMCD is not actually determined only by the imaginary part εxy of the off-diagonal element of the dielectric tensor, as has been widely accepted. In fact, the real part εxy of the off-diagonal element will substantially mix into the measured RMCD results by another oscillatory cos θ form. It can even reverse the sign of RMCD, when the Gal_xMnxAs layer becomes thicker. The main aspects of these predictions were used to reasonably explain the RMCD results measured in three different types of samples. Our work will bring about a reconsideration of how to correctly explain RMCD results.

Study of depth-dependent tetragonal distortion of quaternary AlInGaN epilayer by Rutherford backscattering/channeling

A 240-nm thick Al0.4In0.02Ga0.58N layer is grown by metal organic chemical vapour deposition, with an over 1-μm thick GaN layer used as a buffer layer on a substrate of sapphire （0001）. Rutherford backscattering and channeling are used to characterize the microstructure of AlInGaN. The results show a good crystalline quality of AIInGaN （χmin = 1.5%） with GaN buffer layer. The channeling angular scan around an off-normal {1213} axis in the {1010} plane of the AlInGaN layer is used to determine tetragonal distortion eT, which is caused by the elastic strain in the AIInGaN. The resulting AlInGaN is subjected to an elastic strain at interracial layer, and the strain decreases gradually towards the near-surface layer. It is expected that an epitaxial AlInGaN thin film with a thickness of 850 nm will be fully relaxed （^eT = 0）.

First-principles study of the co-effect of carbon doping and oxygen vacancies in ZnO photocatalyst

Although tuning band structure of optoelectronic semiconductor-based materials by means of doping single defect is an important approach for potential photocatalysis application,C-doping or oxygen vacancy(Vo)as a single defect in ZnO still has limitations for photocatalytic activity.Meanwhile,the influence of co-existence of various defects in ZnO still lacks sufficient studies.Therefore,we investigate the photocatalytic properties of ZnOx C0.0625(x=0.9375,0.875,0.8125),confirming that the co-effect of various defects has a greater enhancement for photocatalytic activity driven by visible-light than the single defect in ZnO.To clarify the underlying mechanism of co-existence of various defects in ZnO,we perform systematically the electronic properties calculations using density functional theory.It is found that the coeffect of C-doping and Vo in ZnO can achieve a more controllable band gap than doping solely in ZnO.Moreover,the impact of the effective masses of ZnO_(x)C_(0.0625)(x=0.9375,0.875,0.8125)is also taken into account.In comparison with heavy Vo concentrations,the light Vo concentration(x=0.875)as the optimal component together with C-doping in ZnO,can significantly improve the visible-light absorption and benefit photocatalytic activity.

Diluted magnetic characteristics of Ni-doped AIN films via ion implantation

The structural and magnetic properties, as well as the mechanism of magnetization, of Ni-implanted A1N films were studied. A1N was deposited on A1203 substrates by metalorganic chemical vapor deposition （MOCVD）, and subsequently Ni ions were implanted into the A1N films by Metal Vapor Arc （MEVVA） sources at an energy of 100 keV for 3 h. The films were annealed at 900~C for 1 h in the furnace in order to transfer the Ni ions from interstitial sites to substitutional sites in A1N, thus activating the Ni3＋ ions. Characterizations were performed in situ using X-ray diffraction （XRD）, X-ray photoemis- sion spectroscopy （XPS）, and vibrating sample magneto- metry （VSM）, which showed that the films have a wurtzite structure without the formation of a secondary phase after implanting and annealing. Ni ions were successfully implanted into substitutional sites of AlN films, and the chemical bonding states are Ni-N. The apparent hysteresis loops prove that the films exhibited magnetism at 300 K. The room temperature （RT） saturation magnetization moment （Ms） and eoercivity （He） values were about 0.36 emu/g and 35.29 Oe, respectively. From the first-principles calculation, a total magnetic moment of 2.99 ~tB per supercell is expected, and the local magnetic moment of a NiN4 tetrahedron, 2.45 gB, makes the primary contribu- tion. The doped Ni atom hybridizes with four nearby N atoms in a NiN4 tetrahedron; then the electrons of the N atoms are spin-polarized and couple with the electrons of the Ni atom with strong magnetization, which results in magnetism. Therefore, the p-d exchange mechanism between Ni-3d and N-2p can be the origin of the magnetism. It is expected that these room temperature, ferromagnetic, Ni-doped A1N films will have many potential applications as diluted magnetic semiconductors.

物理气相输运法生长AlN六方微晶柱

采用物理气相输运法（Physical Vapor Transport, PVT）, 在1700 - 1850°C生长温度下制备出AlN六方微晶柱; 晶柱长度在1 cm左右, 宽度在200 -400 μm, 光学显微镜下观察为六棱柱形状并呈透明浅黄色光泽; 扫描电子显微镜和原子力显微镜测试表明： AlN晶柱表面为整齐台阶状形貌, 台阶宽度为2- 4 μm, 高度在几个纳米; 拉曼光谱测试AlN晶柱具有良好结晶质量。PVT 法生长AlN六方微晶柱主要是在偏低温度下AlN晶体生长速率较慢, Al原子和N原子有足够时间迁移到能量较低位置结晶生长, 进而沿着〈0001〉方向形成柱状结构。AlN六方微晶柱是对一维半导体材料领域的补充, 通过对晶柱尺寸及杂质控制的进一步研究, 有望在微型光电器件领域表现出应用价值。

Growth and properties of wide spectral white light emitting diodes

Wide spectral white light emitting diodes have been designed and grown on a sapphire substrate by using a metal-organic chemical vapor deposition system. Three quantum wells with blue-light-emitting, green-light-emitting and red-light-emitting structures were grown according to the design. The surface morphology of the film was observed by using atomic force microscopy. The films were characterized by their photoluminescence measurements. X-ray diffraction t9/2/9 scan spectroscopy was carried out on the multi-quantum wells. The secondary fringes of the symmetric ω/2θ X-ray diffraction scan peaks indicate that the thicknesses and the alloy compositions of the individual quantum wells are repeatable throughout the active region. The room temperature photoluminescence spectra of the structures indicate that the white light emission of the multi-quantum wells is obtained. The light spectrum covers 400 700 nm, which is almost the whole visible light spectrum.

Implant Compositional Disordering on InGaAs/InP MQW Structures

Some new results of implant disordering on InP based MQW structures by implanted compositional disordering are presented. The energy shift of PL peak depends on ion species, ion dose, annealing conditions and target temperature. The results indicate that the nonactive ions such as F+ and Ne+ are the best candidates for IICD, the ion dose which caused biggest blue shift is around 1 × 10 14 cm-2 for room temperature implantation and 5 × 10 14 cm-2 for an elevated implanted temperature of 200 ℃ and the optimum annealing condition is approximately 750 ℃ for 30 s. AES and TEM characterization suggests that ion bombardment by nonelectrically active ions such as F+, Ne+ induced same amount of layer interdiffusion which results in the band gap blue shift due to the compositional changes.

稀土元素Gd掺杂氮化物半导体在自旋电子器件中的应用（英文）

本研究利用分子束外延的方法生长了Gd掺杂氮化物半导体。根据X线衍射和XAFS测定未有发现第二相的析出。观察到了来自In Gd Ga N的光致发光,发光峰随着In N的摩尔份数的变化而变化。这些材料在室温明显地观测到了磁滞曲线。Si共掺杂的Ga Gd N超晶格显示出了超大的磁矩,其原因可归于载流子诱发铁磁。最后,说明了这一材料在自旋发光二极管中的应用。

具有择优取向的GaN粉末的制备与性能研究

采用管式炉通以流动氨气煅烧β-Ga_2O_3的方法制备六方纤锌矿GaN,利用XRD,SEM,TEM对所制备的Ga N的结构、形貌进行表征和分析,使用荧光光度计采集GaN的光致发光光谱进行发光性能研究.结果表明,GaN具有(002)择优取向,其颗粒外形和尺寸均与原料相似,系由几十纳米的晶片团聚而成的棒状颗粒所组成;GaN的近带边发射峰为346 nm(3.584 eV),相比较块材的近带边发射峰有19 nm(187 meV)的蓝移.

Tunnel junctions in a III-V nanowire by surface engineering

We demonstrate a simple way of fabricating high performance tunnel devices from p-doped InAs nanowires by tailoring the n-doped surface accumulation layer inherent to InAs surfaces. By using appropriate ammonium sulfide based surface passivation before metallization without any further thermal treatment, we demonstrate characteristics of tunnel p-n junctions, namely Esaki and backward diodes, with figures of merit better than previously published for InAs homojunctions. The further optimization of both the surface doping, in a quantitative way, and the device geometry allows us to demonstrate that these nanowire-based technologically-simple diodes have promising direct current characteristics for integrated high frequency detection or generation.

Insight of surface treatments for CMOS compatibility of InAs nanowi

A CMOS compatible process is prese nted in order to grow self-catalyzed InAs nano wires on silic on by molecular beam epitaxy. The crucial step of this process is a new in-situ surface preparation under hydrogen (gas or plasma) during the substrate degassing combined with an in-situ arsenic ann eali ng prior to growth. Morphological and structural characterizati ons of the InAs nano wires are prese nted and growth mecha nisms are discussed in detail. The major in flue nee of surface termi nation is exposed both experime ntally and theoretically using statistics on ensemble of nanowires and density functional theory (DFT) calculations. The differences observed between Molecular Beam Epitaxy (MBE) and Metal Organic Vapor Phase Epitaxy (MOVPE) growth of I nAs nano wires can be explai ned by these differe nt surfaces termi nations. The transition between a vapor solid (VS) and a vapor liquid solid (VLS) growth mechanism is presented. Optimized growth conditions lead to very high aspect ratio nano wires (up to 50 nm in diameter and 3 micron in len gth) without passi ng the 410℃ thermal limit, which makes the whole process CMOS compatible. Overall, our results suggest a new method for surface preparation and a possible tuning of the growth mechanism using different surface termi nations.

Effect of Zn doping on electronic structure and optical properties zincblende GaN(A DFT+U insight)

The development of new materials,having exceptional properties in comparison to existing materials is highly required for bringing advancement in electronic and optoelectronic technologies.Keeping this fact,we investigated structural,electronic,and optical properties of zincblende GaN doped with selected Zn concentrations(6.25%,12.50%,and 18.70%),using the first-principle calculations based on density functional theory with GGA+U.We conducted the entire study using the WIEN2K code.In this study,we calculated various significant parametric quantities such as cohesive energies,formation energies,bulk moduli,and lattice constants along with the study of optical and electronic properties by substituting Ga atoms with Zn atoms in 1×2×2 supercell.The structural stability is confirmed by studying the phonon dispersion curves which suggest that Zn:GaN material is stable against the 6.25%and 18.70%Zn concentrations while for 12.50%,it shows instability.The Hubbard values U=0,2,4,6 eV were added to GGA and the electronic properties were improved with the U=6 eV.Optical absorption was blue shifted while the refractive index and dielectric constant were increased with increasing the Zn concentrations.Electronic properties are enhanced due to the prime contribution of cations(Zn)3ri states.The optical and electronic properties are further discussed in detail in the entire study.