Epitaxial lateral overgrowth of InP by liquid-phase epitaxy on InP (0 0 1), (1 1 1)A,B and (1 1 0) surfaces

The epitaxial lateral overgrowth (ELO) was performed on {0 0 1}, {1 1 1}A,B and {1 1 0} oriented InP by liquid-phase epitaxy at constant growth temperature (450–650°C). According to the observations of cross-sectional shape, the orientation dependence of the vertical growth rate was determined to be {1 1 0}>{1 1 1}A,B>{1 0 0} under the present experimental conditions. The etch pit density in the ELO layer was lower than on openings. In PL mapping observations, PL properties were improved on the ELO layer.     

Characterization of InP grown by OMVPE using trimethylindium and tertiarybutylphosphine (TBP) at low V/III ratios and reduced TBP partial pressures

We report an OMVPE growth process for InP using trimethylindium (TMI) and tertiarybutylphosphine (TBP), a V/III ratio of 15, and a TBP partial pressure of 0.5 Torr. Growth is initiated with a 0.1 μm buffer layer employing a ramped TBP flow. Results are presented for InP grown with two different samples of both TMI and TBP and compared to previous experimental results and theoretical predictions. Good surface morphology is obtained from 540 to 600° C. The net carrier concentrations, N_d-N_a, decrease with increasing growth temperature—but never fall below 1.3 × 10¹⁶ cm^-3. Mobilities of 3990 and 11200 cm²/V.sec are observed at 300 and 77 K, respectively. At 77 K, we infer a compensation ratio of ∼0.4, independent of N_d-N_a. Photoluminescence measurements at 6 K show intense near bandgap emission with a full width half maximum proportional to N_d-N_a. Weak emission is also observed from carbon acceptors, independent of growth temperature. Secondary ion mass spectroscopy measurements are performed on an InP wafer grown with four different temperatures. The observed sulfur concentration drops from 1 × 10¹⁸ to 6 × 10¹⁶ cm^-3 with increasing growth temperature. This confirms that sulfur is an important residual impurity in TBP. The observed carbon concentration is 4–6 × 10¹⁶ cm^-3, regardless of growth temperature.     

Capacitance-voltage analysis of InAs quantum dots grown on InAlAs/InP(0 0 1)

The electronic properties of InAs quantum dots (QDs) grown on InAlAs/InP(0 0 1) were studied by using capacitance-voltage (C-V) analysis and photoluminescence (PL) measurements. The level positions of electrons and holes could be studied separately by using n- and p-type InAlAs matrices, respectively. The holes are found to be more confined than electrons in these kinds of dots.     

In situ observation of surface morphology of InP grown on singular and vicinal (001) substrates

Surface morphology of InP layers is monitored during organometallic vapor phase epitaxy using an in situ diffuse laser light scattering technique. Changes in the diffuse scatter signal are noted for several substrate orientations near the (001) plane and at various growth temperatures. The diffuse scatter signal is shown to be a semi-quantitative indicator of surface roughness through post-growth examination of the samples with phase contrast optical microscopy and atomic force microscopy. Singular substrates consistently have almost featureless surfaces and very little diffuse scattering during growth. Vicinal substrates display a more complicated morphological evolution which cannot be deduced from the diffuse scattering alone but which does produce characteristic changes in diffuse scattering.     

Self-organization phenomenon of strained InGaAs on InP (311) substrates grown by metalorganic vapor phase epitaxy

We have demonstrated that a self-organization phenomenon occurs in strained InGaAs system on InP (311) substrates grown by metalorganic vapor phase epitaxy. This suggests that a similar formation process of nanocrystals exists not only on the GaAs (311)B substrate but also on the InP (311)B substrate. However, the ordering and the size homogeneity of the self-organized nanocrystals are slightly worse than those of the InGaAs/AlGaAs system on the GaAs (311)B substrate. The tensilely strained condition of a InGaAs/InP system with growth interruption in a PH₃ atmosphere reveals a surface morphology with nanocrystals even on the InP (100) substrate. It was found that strain energy and high growth temperature are important factors for self-organization on III-V compound semiconductors. Preliminary results indicate that the self-organized nanostructures in strained InGaAs/InP systems on InP substrates exhibit room temperature photoluminescent emissions at a wavelength of around 1.3 p.m.     

Fluorescence EXAFS analysis of ErP grown on InP by organometallic vapor phase epitaxy using a new organometal Er(EtCp)3

We have investigated local structures of ErP grown by organometallic vapor phase epitaxy Er source: tris(ethylcyclopentadienyl)erbium (Er(EtCp)₃ by extended X-ray absorption fine structure (EXAFS) measurement. The EXAFS analysis revealed that NaCl-type ErP and Er–O(–C) compounds coexisted in the case of ErP growth by using Er(EtCp)₃. The NaCl-type ErP was preferentially formed on InP(1 1 1)A compared with InP(0 0 1) and InP(1 1 1)B. It is considered that formation of unexpected Er–O(–C) compounds is due to low but significant concentration of residual O and/or C in Er(EtCp)₃.     

Super-flat interfaces in In0.53Ga0.47As/In0.52Al0.48As quantum wells grown on (411)A InP substrates by molecular beam epitaxy

Effectively atomically flat interfaces over a macroscopic area (“(411)A super-flat interfaces”) were successfully achieved in In_0.53Ga_0.47As/In_0.52Al_0.48As quantum wells (QWs) grown on (411)A InP substrates by molecular beam epitaxy (MBE) at a substrate temperature of 570°C and V/III=6. Surface morphology of the In_0.53Ga_0.47As/In_0.52Al_0.48As QWs was smooth and featureless, while a rough surface of those simultaneously grown on a (100) InP substrate was observed. Photoluminescence (PL) linewidths at 4.2 K from the (411)A QWs with well width of 0.6–12 nm were 20–30 % narrower than those grown on a (100) InP substrate and also they are almost as narrow as each of split PL peaks for those of growth-interrupted QWs on a (100) InP substrate. In the case of the (411)A QWs, only one PL peak with very narrow linewidth was observed from each QW over a large distance (7 mm) on a wafer.     

Growth and fabrication of AlGaN/GaN HEMT based on Si(1 1 1) substrates by MOCVD

AlGaN/GaN high electron mobility transistor (HEMT) hetero-structures were grown on the 2-in Si (1 1 1) substrate using metal-organic chemical vapor deposition (MOCVD). Low-temperature (LT) AlN layers were inserted to relieve the tension stress during the growth of GaN epilayers. The grown AlGaN/GaN HEMT samples exhibited a maximum crack-free area of 8 mm×5 mm, XRD GaN (0 0 0 2) full-width at half-maximum (FWHM) of 661 arcsec and surface roughness of 0.377 nm. The device with a gate length of 1.4 μm and a gate width of 60 μm demonstrated maximum drain current density of 304 mA/mm, transconductance of 124 mS/mm and reverse gate leakage current of 0.76 μA/mm at the gate voltage of −10 V.     

Optical and crystallographic properties of high perfection InP grown on Si(111)

The growth of InP by low-pressure metalorganic chemical vapor deposition on vicinal Si(111), misoriented 3° toward [1-10], is reported. Antiphase domain-free InP is obtained without any preannealing of the Si substrate. Crystallographic, optical, and electrical properties of the layers are significantly improved as compared to the best reported InP grown on Si(001). The high structural perfection is demonstrated by a full width at half maximum (FWHM) of 121 arcs for the (111) Bragg reflex of InP (thickness = 3.4 μm) as obtained by double crystal x-ray diffraction. The low-temperature photoluminescence (PL) efficiency is 70% of that of homoepitaxially grown InP layers. The FWHM of the near-gap PL peak is only 2.7 meV as compared to 4.5 meV of the best material grown on Si(001). For the first time, InP:Fe layers with semi-insulating characteristics (ρ > 3 × 10⁷ Ω-cm) have been grown by compensating the low residual background doping using ferrocene. Semi-insulating layers are prerequisite for any device application at ultrahigh frequencies.     

Solid phase epitaxial growth of Dy-germanide films on Ge(0 0 1) substrates

Dy thin films are grown on Ge(0 0 1) substrates by molecular beam deposition at room temperature. Subsequently, the Dy film is annealed at different temperatures for the growth of a Dy-germanide film. Structural, morphological and electrical properties of the Dy-germanide film are investigated by in situ reflection high-energy electron diffraction, and ex situ X-ray diffraction, atomic force microscopy and resistivity measurements. Reflection high-energy electron diffraction patterns and X-ray diffraction spectra show that the room temperature growth of the Dy film is disordered and there is a transition at a temperature of 300-330 °C from a disordered to an epitaxial growth of a Dy-germanide film by solid phase epitaxy. The high quality Dy₃Ge₅ film crystalline structure is formed and identified as an orthorhombic phase with smooth surface in the annealing temperature range of 330-550 °C. But at a temperature of 600 °C, the smooth surface of the Dy₃Ge₅ film changes to a rough surface with a lot of pits due to the reactions further.     

Optical anisotropy and photoluminescence temperature dependence for self-assembled InAs quantum islands grown on vicinal (001) InP substrates

In this paper, we report on a detailed investigation of the effect of misorientated InP(001) substrates on the optical properties of InAs quantum islands grown by molecular beam epitaxy in the Stranski-Krastanow regime. Temperature-dependent photoluminescence and polarization of photoluminescence (PPL) are studied. PPL shows a high degree of linear polarization, near 40%, for the sample grown on the substrate with 2° off miscut angle towards [110] direction (2°F) and only 16% for the sample grown on the substrate with 2° off miscut angle towards [010] direction (2°B). This result pointing out the growth of InAs quantum wires (QWr) on 2°F substrate and of quasi-isotropic InAs quantum dots (QD) on 2°B substrate. The luminescence remains strong at 300 K as much as 36% of that at 8 K, indicating a strong spatial localization of the carriers in the InAs QIs grown on InP(001).     

(Ga,Mn)As on patterned GaAs(0 0 1) substrates: Growth and magnetotransport

A new type of (Ga,Mn)As microstructures with laterally confined electronic and magnetic properties has been realized by growing (Ga,Mn)As films on -oriented ridge structures with (1 1 3)A sidewalls and (0 0 1) top layers prepared on GaAs(0 0 1) substrates. The temperature- and field-dependent magnetotransport data of the overgrown structures are compared with those obtained from planar reference samples revealing the coexistence of electronic and magnetic properties specific for (0 0 1) and (1 1 3)A (Ga,Mn)As on a single sample.     

Molecular beam epitaxial growth of MgZnCdSe on (100) InP substrates

Wide-gap II-VI MgZnCdSe quaternary compounds were grown on InP substrates by molecular beam epitaxy, for the first time. Changing the Mg composition (x = 0 to 0.63), various Mg_x(Zn_yCd_{1_y})_{1_x}Se lattice-matched to InP were grown. Mirror-like surface morphologies and streaky reflection high energy electron diffraction patterns of MgZnCdSe were obtained. With increased Mg compositions, the band-edge emissions wavelength in photoluminescence spectra was shifted from 572 nm (2.17 eV) to 398 nm (3.12 eV) at 15K. Furthermore, the absolute PL peak intensity increased drastically with increased band-edge emission, being accompanied by a relative decrement in the deep level emission intensities were also observed.     

InP（Yb）晶体结构和发光特性的研究

用离子注入法配合优化退火新技术制成了一种高效发光材料ＩｎＰ（Ｙｂ）；用高灵敏度激光光谱仪测量了该材料的发光特性（ＰＬ），并研究了离子注入和退火过程中发光特性的变化，对ＰＬ谱峰作出辨认；用Ｘ射线衍射谱（ＸＤＳ）测量分析晶格结构和注入损伤（缺陷）；研究了原材料的掺杂（Ｓｎ）对发光特性的影响；较深入地探讨了该材料的发光机制，并用一改进ＲＥ发光中心模型阐明该材料的激发发光过程。     

K0.9Li0.1（Ta0.5Nb0.5）O3晶体压电应变系数的测量

用准静态ｄ＿（３３）测量仪和干涉法相结合。测量了Ｋ＿（０．９）Ｌｉ＿（０．１）（Ｔａ＿（０．５）Ｎｂ＿（０．５）Ｎｂ＿（０．５））Ｏ＿３晶体的压电应变系数。结果为：ｄ＿（３３）＝８６．０，ｄ＿（３３）＝一２９．５，ｄ＿（１５）＝１１２．９×１０￣（－１２）Ｃ／Ｎ．     

Atomic structures of Au and Ag films epitaxially grown on the InP(001)-p(2 × 4) surface

Thin films of Au and Ag deposited onto the InP(001)-p(2 × 4) surface at room temperature have been characterized by means of combined surface-layer analysis of low energy electron diffraction, reflection high energy electron diffraction, Auger electron spectroscopy, and Rutherford backscattering spec-troscopy-channeling techniques. It has been found that the Au film grows epitaxially in the layer-by-layer mode along the <001> direction, while the Ag film grows in the <110> direction in the Stranski-Krastanov mode. The unit cell of a face-centered cubic lattice of the Au film is rotated azimuthally by 45° with respect to the unit cell of a zinc-blende lattice of the InP substrate. The islands of Ag(110) crystallites prefer to orient their (100) faces along the direction of the 4 times superlattice of the InP(001)-p(2 × 4) surface. The analysis of the RBS-channeling minimum yield of 1.5 MeVHe⁺ ions incident along the [001] direction of the InP(OOl) substrate shows that both the epitaxially grown Au film and Ag crystallite of less than 20Å in thickness are excellent in crystalline quality.     

Convex corners undercutting and rhombus compensation in KOH with and without IPA solution on (1 1 0) silicon

The present investigation introduces convex corners undercutting and results of rhombus compensation patterns in 40% aqueous KOH solution and in KOH saturated with isopropanol (IPA) solution. All experiments are carried out on (1 1 0) silicon at 70 °C. Undercuts take place on convex corners in both solutions. Moreover, the front etch planes governing undercut vary with solutions. Rhombus compensations are used to correct the undercut. Perfect acute corner without residue is obtained, and there are only some residue structures on both sides of obtuse convex corners in KOH with IPA solution, which are better results than those in pure aqueous KOH solution.     

Epitaxial growth of Dy2O3 thin films on epitaxial Dy-germanide films on Ge(0 0 1) substrates

Ultra-thin films of Dy are grown on Ge(0 0 1) substrates by molecular beam deposition near room temperature and immediately annealed for solid phase epitaxy at higher temperatures, leading to the formation of DyGe_x films. Thin films of Dy₂O₃ are grown on the DyGe_x film on Ge(0 0 1) substrates by molecular beam epitaxy. Streaky reflection high energy electron diffraction (RHEED) patterns reveal that epitaxial DyGe_x films grow on Ge(0 0 1) substrates with flat surfaces. X-ray diffraction (XRD) spectrum suggests the growth of an orthorhombic phase of DyGe_x films with (0 0 1) orientations. After the growth of Dy₂O₃ films, there is a change in RHEED patterns to spotty features, revealing the growth of 3D crystalline islands. XRD spectrum shows the presence of a cubic phase with (1 0 0) and (1 1 1) orientations. Atomic force microscopy image shows that the surface morphology of Dy₂O₃ films is smooth with a root mean square roughness of 10 Å.     

基于低温In_xGa_(1-x)P组分渐变缓冲层的InP/GaAs异质外延

采用低温GaAs与低温组分渐变InxGa1-xP作为缓冲层,利用低压金属有机化学气相外延(LP-MOCVD)技术,在GaAs(001)衬底上进行了InP/GaAs异质外延实验。实验中,InxGa1-xP缓冲层选用组分线性渐变生长模式(xIn0.49→1)。通过对InP/GaAs异质外延样品进行双晶X射线衍射(DCXRD)测试,并比较1.2μm厚InP外延层(004)晶面ω扫描及ω-2θ扫描的半高全宽(FWHM),确定了InxGa1-xP组分渐变缓冲层的最佳生长温度为450℃、渐变时间为500s。由透射电子显微镜(TEM)测试可知,InxGa1-xP组分渐变缓冲层的生长厚度约为250nm。在最佳生长条件下的InP/GaAs外延层中插入生长厚度为48nm的In0.53Ga0.47As,并对所得样品进行了室温光致发光(PL)谱测试,测试结果表明,中心波长为1643nm,FWHM为60meV。     

Electrical properties of InAlAs/InAsxP1-x/InP composite-channel modulation-doped structures grown by solid source molecular beam epitaxy

We report on the electrical characteristics of the two-dimensional electron gas (2DEG) formed in an InAlAs/InAs_xP_1-x/InP pseudomorphic composite-channel modulation-doped (MD) structure grown by solid source (arsenic and phosphorus) molecular beam epitaxy (SSMBE). The As composition, x, of strained InAs_xP_1-x was determined by x-ray diffraction analysis of InP/InAs_xP_1-x/InP multi-quantum wells (MQWs) with compositions of x=0.14 to x=0.72. As the As composition increases, the room temperature sheet resistance of InAlAs/InAs_xP_1-x/InP composite-channel MD structures grown over a range of As compositions decreased from 510 to 250 Ω/cm², resulting from the greater 2DEG confinement and lower electron effective mass in the InAs_xP_1-x channel as x increases. The influence of growth conditions and epitaxial layer designs on the 2DEG mobility and concentration were investigated using 300 K and 77 K Hall measurements. As the exposure time of the As₄ flux on the growth front of InAs_xP_1-x increased during growth interruptions, the 2DEG mobility, in particular the 77K mobility, was considerably degraded due to increased roughness at the InAlAs/InAs_xP_1-x interface. For the InAlAs/InAs_0.6P_0.4/InP composite-channel MD structure with a spacer thickness of 8 nm, the room temperature 2DEG mobility and density were 7200 cm²/Vs and 2.5 × 10¹² cm⁻², respectively. These results show the great potential of the InAlAs/InAs_xP_1-x/InP pseudomorphic composite-channel MD heterostructure for high frequency, power device applications.