Lattice-matched InP Research Articles

Prediction of mechanical properties of In1-x GaxAsyP1-y lattice-matched to different substrates using artificial neural network (ANN)

ABSTRACT The mechanical properties, namely the elastic constants (C11, C12, and C44), bulk B, shear Cs, and Young’s modulus Y0, of the In1-xGaxAsyP1-y lattice-matched GaAs and InP substrates, were estimated using an artificial neural network (ANN method). This study aimed to create ANN networks that facilitate the estimation of the mechanical properties of alloys subjected to different temperatures and hydrostatic pressures. We aimed to predict the mechanical properties of InGaAsP alloys matched to InP and GaAs substrates as a function of temperature and hydrostatic pressure. ANN learning was performed based on the results validated by the empirical pseudopotential method data within the virtual crystal approximation, including the actual disorder potential. An ANN is a nonlinear process modeling technique frequently encountered in materials science. The predictive curves show high reliability, and underline the importance of using this approach to replace the time-consuming and costly experimental test, as well as to predict the mechanical response of the material where conventional modeling approaches have failed. Our method can consolidate the theoretical references found in the literature, it can also serve the field of engineering the mechanical properties of semiconductors, facilitate the successful design of optoelectronic devices, and serve future experimental works.

Revisiting the van der Waals Epitaxy in the Case of (Bi0.4Sb0.6)2Te3 Thin Films on Dissimilar Substrates.

Ultrathin films of the ternary topological insulator (BiSb)Te are fabricated by molecular beam epitaxy. Although it is generally assumed that the ternary topological insulator tellurides grow by van der Waals epitaxy, our results show that the influence of the substrate is substantial and governs the formation of defects, mosaicity, and twin domains. For this comparative study, InP (111)A, AlO (001), and SrTiO (111) substrates were selected. While the films deposited on lattice-matched InP (111)A show van der Waals epitaxial relations, our results point to a quasi-van der Waals epitaxy for the films grown on substrates with a larger lattice mismatch.

Experimental Demonstration of the Impact of the Parameters of Floating Guard Ring on Planar InP/InGaAs-Based Avalanche Photodiodes’ Performance and Its Optimization

Suppression pre-breakdown in planar separated absorption, grading, charge and multiplication (SAGCM) avalanche photodiodes (APDs) with the help of Floating Guard Ring (FGR) is still a research hotspot. In this paper, a lattice-matched InP&#x002F;InGaAs-based SAGCM structure is grown by Metal-Organic Chemical Vapor Deposition and thus the planar 50 &#x03BC;m photosensitive area APDs with different FGR structures are fabricated using zinc diffusion process. The effects of the different lengths of FGR (4 &#x03BC;m, 8 &#x03BC;m, 12 &#x03BC;m, 16 &#x03BC;m), and the different distances between FGR and the Zn diffused p&#x002B; region (4 &#x03BC;m, 6 &#x03BC;m, 8 &#x03BC;m, 10 &#x03BC;m) on the optoelectrical characteristics are deeply studied. The results from optical microscope, scanning electron microscope and current-voltage curves reveal that there is an optimal length and distance for the punch-through and breakdown voltage. Furthermore, the nA-level dark current, gain (<i>M</i>) of up to 10 at breakdown voltage, responsibility as high as 9.01 A&#x002F;W at <i>M</i> &#x003D; 10 and quantum efficiency equaling to 72&#x0025; are also tested and calculated, proving the good performance of our devices. The optimized FGR parameters and related structure are expected to be helpful for obtaining high-performance, small-size InP&#x002F;InGaAs-based APDs.

(Invited) Monolithic Integration of III-V As- and P-Based Devices on Si through Direct MBE Growth and Using Lattice Engineered Substrates

Mainstream silicon (Si) CMOS technology is finally experiencing limitations of pure Si-based material and process. For digital electronics, to extend Moore’s law, the industry increasingly is investigating alternative materials and technologies to enhance channel transport properties and reduce power dissipation for future generation transistor circuitry. Heterogeneous integration of compound III-V semiconductor devices on Si may realize high performance integrated circuits for analog and digital applications and can incorporate optoelectronic components for high-speed data transfer. Such integration provides the combined advantages of high volume production of Si-based electronic circuitry with superior high-speed performance of III-V components. At IQE, we developed molecular beam epitaxy (MBE) growth processes for the production of high quality III-V based transistor structures monolithically integrated onto CMOS-compatible substrates by direct MBE growth on Si wafers and also by utilization of specialized Si-on-Lattice-Engineered-Substrate (SOLES) substrates. Through work with industry partners, IQE has grown InP-based high electron mobility transistor (HEMT) and quantum well field effect transistor (QWFET) structures directly on Si substrates by MBE. Following a high-K gate dielectric fabrication process, QWFET devices demonstrated high transconductance of 1750μS/μm and high drive current of 0.49mA/μm at VDS=0.5V. [1] As part of a program funded by the US Defense Advanced Research Projects Agency, IQE developed a direct MBE growth approach of an InP-based heterojunction bipolar transistor (HBT) structure on the SOLES substrates, and together with our collaborators successfully created clusters of high-speed III-V HBT circuitry monolithically integrated side-by-side with Si CMOS on the same wafer. [2] In this paper, we will discuss structural and electronic properties of epitaxial device material, including dislocation filtering in the mismatched metamorphic buffers, and compare performance of devices fabricated on Si with reference material grown on lattice-matched InP substrates. [1] Radosavljevic, M.; Chu-Kung, B.; Corcoran, S.; Dewey, G.; Hudait, M. K.; Fastenau, J. M.; Kavalieros, J.; Liu, W. K.; Lubyshev,D.; Metz, M.; Millard, K.; Mukherjee, N.; Rachmady, W.; Shah, U.; Chau, R. (2009), IEDM Tech. Dig., p.13.1. [2] W. K. Liu, D. Lubyshev, J. M. Fastenau, Y. Wu, M. T. Bulsara, E. A. Fitzgerald, M. Urteaga, W. Ha, J. Bergman, B. Brar, W. E. Hoke, J. R. LaRoche, K. J. Herrick, T. E. Kazior, D. Clark, D. Smith, R. F. Thompson, C. Drazek, and N. Daval, J. Crystal Growth, 311, 1979 (2009).

Low interface trap density Al2O3/In0.53Ga0.47As MOS capacitor fabricated on MOCVD-grown InGaAs epitaxial layer on Si substrate

A low interface trap density (Dit) Al2O3/In0.53Ga0.47As/Si MOS capacitor fabricated on an In0.53Ga0.47As heterostructure layer directly grown on a 300 mm on-axis Si(100) substrate by MOCVD with a very thin buffer layer is demonstrated. Compared with the MOS capacitors fabricated on the In0.53Ga0.47As layer grown on the lattice-matched InP substrate, the Al2O3/In0.53Ga0.47As MOS capacitors fabricated on the Si substrate exhibit excellent capacitance–voltage characteristics with a small frequency dispersion of approximately 2.5%/decade and a low interface trap density Dit close to 5.5 × 1011 cm−2 eV−1. The results indicate the potential of integrating high-mobility InGaAs-based materials on a 300 mm Si wafer for post-CMOS device application in the future.

Local electrical properties of n-AlInAs/i-GaInAs electron channel structures characterized by theprobe-electron-beam-induced current technique

We developed a probe-electron-beam-induced current (probe-EBIC) technique to investigate the electrical properties of n-Al(0.48)In(0.52)As/i-Ga(0.30)In(0.70)As electron channel structures for a high-electron-mobility transistor, grown on a lattice-matched InP substrate and lattice-mismatched GaAs (001) and Si (001) substrates. EBIC imaging of planar surfaces at low magnifications revealed misfit dislocations originating from the AlInAs-graded buffer layer. The cross-sections of GaInAs channel structures on an InP substrate were studied by high-magnification EBIC imaging as well as cathodoluminescence (CL) spectroscopy. EBIC imaging showed that the structure is nearly defect-free and the carrier depletion zone extends from the channel toward the i-AlInAs buffer layer.

Multi-Watt Semiconductor Disk Laser by Low Temperature Wafer Bonding

We present wafer bonding techniques applied for the first time in integrating GaAs-based distributed Bragg reflectors (DBRs) with InP-based active regions in optically pumped semiconductor disk lasers. The bonding procedures are performed at a modest temperature of 200 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> C and enable multi-watt output powers from 1.3 μm semiconductor disk lasers. These technologies are critical for vertical-cavity lasers emitting in the range 1.3-1.6 μm since monolithically grown lattice-matched InP structures suffer from DBRs with low refractive index contrast and poor thermal conductivity when compared with GaAs-based DBRs.

Molecular beam epitaxy of high structural quality Bi2Se3 on lattice matched InP(111) substrates

Epitaxial layers of the topological insulator Bi2Se3 have been grown by molecular beam epitaxy on laterally lattice-matched InP(111)B substrates. High resolution X-ray diffraction shows a significant improvement of Bi2Se3 crystal quality compared to layers deposited on other substrates. The measured full width at half maximum of the rocking curve is Δω=13 arc sec, and the (ω−2θ) scans exhibit clear layer thickness fringes. Atomic force microscope images show triangular twin domains with sizes increasing with layer thickness. The structural quality of the domains is confirmed on the microscopic level by transmission electron microscopy.

Gate control of surface transport in MBE-grown topological insulator (Bi1−xSbx)2Te3thin films

Topological insulators are quantum materials comprised of an insulating bulk gap and topologically protected metallic surfaces with a Dirac-like band dispersion. To access the Dirac point by transport measurements is a very challenging issue faced in current investigations of these materials. Here we report the electronic state modulation in topological insulator (Bi${}_{1\ensuremath{-}x}$Sb${}_{x}$)${}_{2}$Te${}_{3}$ thin films by means of an ionic-liquid gating. The films with 20 nm thickness were grown on lattice-matched semi-insulating InP substrates by molecular beam epitaxy; the temperature dependencies of resistance of these films clearly indicate their insulating bulk and metallic surface characteristics. The surface state carriers were systematically controlled by using electric-double-layer transistor (EDLT) configurations with ionic-liquid dielectrics. It was demonstrated that the surface state in the (Bi${}_{1\ensuremath{-}x}$Sb${}_{x}$)${}_{2}$Te${}_{3}$-based EDLTs is tuned across the Dirac point, showing ambipolar transport in a topological transport regime.

Room-Temperature Ferromagnetism in (Zn,Mn,Sn)As2 Thin Films Applicable to InP-Based Spintronic Devices

We investigated the growth and magnetic properties of ternary ZnSnAs2 thin films doped with a various degrees of Mn content. It was confirmed that Mn-doped ZnSnAs2 thin films are pseudomorphically grown on nearly lattice-matched InP(001) substrates. Magnetization measurements on Mn-doped ZnSnAs2 thin films revealed a ferromagnetic transition temperature of around 330 K, and clearly showed hysteresis loops even at room temperature. No evidence of magnetic secondary-phase MnAs formation in the host ZnSnAs2 thin films was observed within the limit of our measurement system. We also prepared a trilayer structure consisting of Mn-doped ZnSnAs2 layers and an undoped ZnSnAs2 intermediary layer as a preliminary structure for a tunneling magnetic junction. This structure was confirmed to demonstrate ferromagnetism at room temperature. The present results suggest that diluted ferromagnetic (Zn,Mn,Sn)As2 thin films are one of the most promising building blocks for InP-based spintronic devices.

Ferromagnetic and transport properties of highly Mn-doped ZnSnAs 2 epitaxial layers on InP substrates

Ternary ZnSnAs 2 thin films heavily doped with nominal 10 and 20% Mn content on InP (001) substrates are grown using low-temperature molecular beam epitaxy and their magnetic and transport properties are investigated for the first time. It is found that the Mn-doped ZnSnAs 2 thin films are pseudomorphically grown on nearly lattice-matched InP (001) substrates, and a trace amount of secondary phase MnAs formation is observed by high-resolution X-ray diffraction (HR-XRD) measurements. Magnetization measurements on Mn-doped ZnSnAs 2 thin films reveal that the Curie temperature is around 334 K. Nominal magnetic moments per Mn atom measured from the saturation magnetization of hysteresis loops at 5 K have been estimated as 5.28 and 4.17 μ B for 10% and 20% Mn-doped ZnSnAs 2 thin films, respectively. We have found from Hall effect measurements that the 10% and 20% Mn-doped ZnSnAs 2 films exhibit n-type conduction, in contrast to p-type conduction in ZnSnAs 2 doped with less than 10% Mn. This is likely related to the presence of a certain amount of Mn interstitials or Mn 3+ substitution on Zn site in the samples.

Photoluminescence study of epitaxially grown ZnSnAs2:Mn thin films

The photoluminescence (PL) properties of heavily Mn-doped ZnSnAs2 layers epitaxially grown on nearly lattice-matched semi-insulating InP substrates are studied. PL spectra are obtained for samples with Mn concentrations of 5, 12 and 24 mol% relative to the combined concentrations of Zn and Sn. A broad emission band centered at ∼ 1 eV is detected for Mn-doped layers at room temperature. The emission is a intense broad asymmetric line at low temperatures. The line is reconstructed by superposition of two bands with peak energies of ∼ 0.99 and 1.07 eV, similar to those reported for InP. These bands are superimposed onto a 1.14 eV band with well-resolved phonon structure for the layer doped with 12 % Mn. Recombination mechanism involving the split-off band of the ZnSnAs2 is suggested. Temperature dependence of integrated intensities of the PL bands indicates to thermally activated emission with activation energies somewhat different from those found for InP. Mn substitution at cationic sites increases the concentration of holes which may act as recombination centers. Recombination to the holes bound to Mn ions with the ground state located below the top of the valence band has been proposed as a possible PL mechanism.

Evidence of Pseudomorphic Growth of ZnSnAs2 Epitaxial Layers on Nearly Lattice Matched InP Substrates

ZnSnAs2 epitaxial films of various thicknesses have been grown on InP(001) substrates by molecular beam epitaxy using different growth times. No manifestations of epitaxial layer lattice relaxation such as broadening of the full width at half maximum of high-resolution x-ray diffraction rocking curves, reduction of the ratio of the diffraction peak intensities of the epitaxial layer and the substrate, and extinction of the Pendellosüng fringes were observed with increasing sample thickness. This implies that the epitaxial films remain pseudomorphic with the InP substrate to a thickness of at least 285 nm. Micro-Raman spectroscopy measurements revealed that all the samples exhibited A1 vibrational modes that were similar to those observed in chalcopyrite semiconductors

High-Temperature Thermoelectric Characterization of III–V Semiconductor Thin Films by Oxide Bonding

A device fabrication and measurement method utilizing a SiO2–SiO2 covalent bonding technique is presented for high-temperature thermoelectric characterization of thin-film III–V semiconductor materials that suffer from the sideeffect of substrate conduction at high temperatures. The proposed method includes complete substrate removal, high-temperature surface passivation, and metallization with a Ti-W-N diffusion barrier. A thermoelectric material, thin-film ErAs:InGaAlAs metal/semiconductor nanocomposite grown on a lattice-matched InP substrate by molecular beam epitaxy, was transferred onto a sapphire substrate using the oxide bonding technique at 300C, and its original InP substrate, which is conductive at high temperatures, was removed. Electrical conductivities and Seebeck coefficients were measured from room temperature to 840 K for this material on both the InP and sapphire substrates, and the measurement results clearly show that the InP substrate effect was eliminated for the sample on the sapphire substrate. A strain experiment has been conducted to investigate the effect of strain on electrical conductivity.

Molecular Beam Epitaxy Growth of High Mobility Compound Semiconductor Devices for Integration with Si CMOS

AbstractWe report on a direct epitaxial growth approach for the heterogeneous integration of high speed III-V devices with Si CMOS logic on a common Si substrate. InP-based heterojunction bipolar transistor (HBTs) structures were successfully grown on patterned Si-on-Lattice-Engineered-Substrate (SOLES) substrates using molecular beam epitaxy. DC and RF performance similar to those grown on lattice-matched InP were achieved in growth windows as small as 15×15μm2. This truly planar approach allows tight device placement with InP-HBTs to Si CMOS transistors separation as small as 2.5 μm, and the use of standard wafer level multilayer interconnects. A high speed, low power dissipation differential amplifier was designed and fabricated, demonstrating the feasibility of using this approach for high performance mixed signal circuits such as ADCs and DACs.

Monolithic integration of InP-based transistors on Si substrates using MBE

We report on a direct epitaxial growth approach for the heterogeneous integration of high-speed III–V devices with Si CMOS logic on a common Si substrate. InP-based heterojunction bipolar transistor (HBT) structures were successfully grown on Si-on-lattice-engineered- substrate (SOLES) and Ge-on-insulator-on-Si (GeOI/Si) substrates using molecular beam epitaxy. Structurally, the epiwafers exhibit sharp interfaces and a threading dislocation density of 3.5×10 7 cm −2 as measured by plan-view transmission electron microscopy. HBT devices fabricated on GeOI/Si substrates have current gain of 55–60 at a base sheet resistance of 650–700 Ω/sq, and f t and f max of around 220 GHz. HBT structures with DC and RF performance similar to those grown on lattice-matched InP were also achieved on patterned SOLES substrates with growth windows as small as 15×15 μm 2. These results demonstrate a promising path of heterogeneous integration and selective placement of III–V devices at arbitrary locations on Si CMOS wafers.

Metamorphic Heterostructure InP/GaAsSb/InP HBTs on GaAs Substrates by MOCVD

Good-quality metamorphic InP buffer layers have been successfully grown on GaAs substrates by metal-organic chemical vapor deposition. Characterization by atomic force microscope, transmission electron microscopy, high-resolution X-ray diffraction, and Hall measurements indicated that the layers are of high crystalline quality, good mobility, and excellent surface morphology. On this buffer, we demonstrated the first metamorphic InP/GaAsSb/InP double heterojunction bipolar transistors (DHBTs) with good material quality and device performance. Metamorphic DHBTs showed direct-current and radio-frequency characteristics that are comparable to those grown on lattice-matched InP substrates.

Chemical composition of InAlAs oxides grown on In0.52Al0.48As epilayer lattice matched to InP substrate

This paper represents a chemical composition of InAlAs oxides lattice matched on In0.52Al0.48As epilayer to InP substrate. The thickness of MBE grown In0.52Al0.48As epilayer was about 1.7μm on thick InP(100) substrates. Oxides roughness, surface morphology, chemical composition of oxides interface and depth profiles were characterized by atomic force microscopy (AFM), energy-dispersive X-ray (EDX), and secondary ion mass spectrometry (SIMS) techniques. ‘In’- and ‘As’- rich chemical compositions were obtained at the strain-free oxidation region than the other chemical elements. All these chemical investigations were confirmed by various surface analytical techniques which lead to understand the compositions of strain-relaxed oxidation at the interface between lattice-matched InAlAs epilayer and InP substrate.

Fabrication, structural and magnetic properties of InAlMnAs and InAlAs:MnAs granular thin films

We fabricated In 0.52Al 0.48As:MnAs granular thin films by annealing [(In 0.52Al 0.48) 1− x Mn x ]As alloy thin films at 600 °C. The [(In 0.52Al 0.48) 1− x Mn x ]As thin films were grown on InP(0 0 1) substrates with Mn concentrations x of 0.09 and 0.12 by low-temperature molecular beam epitaxy. We investigated the structural and magneto-optical properties of the In 0.52Al 0.48As:MnAs granular thin films by X-ray diffraction and magnetic circular dichroism, and compared with those of the as-grown [(In 0.52Al 0.48) 1− x Mn x ]As thin films. The In 0.52Al 0.48As:MnAs granular thin films showed a large magneto-optical effect at room temperature. This large magneto-optical effect of the granular materials lattice-matched InP will be useful for InP-based magneto-optical devices operating at room temperature.

Unpinning of the Fermi level at (111)A clean surfaces of epitaxially grown n-type In0.53Ga0.47As

Low-temperature scanning tunneling spectroscopy under ultrahigh vacuum was employed to investigate the (111)A clean surface of n-type In0.53Ga0.47As⁠, grown by molecular beam epitaxy on lattice-matched InP substrates. It was found that the surface Fermi level is located in the conduction band, close to the bulk Fermi level, and can be controlled by varying the dopant concentration in the bulk. This observation was confirmed by determining the dispersion relation of electron standing waves resulting from scattering interferences. Such an unpinning of the surface Fermi level strongly contrasts with the pinning phenomenon observed at the (001) clean surface.