Crystalline InP Research Articles

Wafer-scale heterogeneous integration InP on trenched Si with a bubble-free interface

Heterogeneous integration of compound semiconductors on a Si platform leads to advanced device applications in the field of Si photonics and high frequency electronics. However, the unavoidable bubbles formed at the bonding interface are detrimental for achieving a high yield of dissimilar semiconductor integration by the direct wafer bonding technology. In this work, lateral outgassing surface trenches (LOTs) are introduced to efficiently inhibit the bubbles. It is found that the chemical reactions in InP–Si bonding are similar to those in Si–Si bonding, and the generated gas can escape via the LOTs. The outgassing efficiency is dominated by LOTs’ spacing, and moreover, the relationship between bubble formation and the LOT’s structure is well described by a thermodynamic model. With the method explored in this work, a 2-in. bubble-free crystalline InP thin film integrated on the Si substrate with LOTs is obtained by the ion-slicing and wafer bonding technology. The quantum well active region grown on this Si-based InP film shows a superior photoemission efficiency, and it is found to be 65% as compared to its bulk counterpart.

Efficient ion-slicing of InP thin film for Si-based hetero-integration

Integration of high quality single crystalline InP thin film on Si substrate has potential applications in Si-based photonics and high-speed electronics. In this work, the exfoliation of a 634 nm crystalline InP layer from the bulk substrate was achieved by sequential implantation of He ions and H ions at room temperature. It was found that the sequence of He and H ion implantations has a decisive influence on the InP surface blistering and exfoliation, which only occur in the InP pre-implanted with He ions. The exfoliation efficiency first increases and then decreases as a function of H ion implantation fluence. A kinetics analysis of the thermally activated blistering process suggests that the sequential implantation of He and H ions can reduce the InP thin film splitting thermal budget dramatically. Finally, a high quality 2 inch InP-on-Si(100) hetero-integration wafer was fabricated by He and H ion sequential implantation at room temperature in combination with direct wafer bonding.

Nonpolar-Oriented Wurtzite InP Nanowires with Electron Mobility Approaching the Theoretical Limit.

As an important semiconductor nanomaterial, InP nanowires (NWs) grown with a typical vapor-liquid-solid mechanism are still restricted from their low electron mobility for practical applications. Here, nonpolar-oriented defect-free wurtzite InP NWs with electron mobility of as high as 2000 cm2 V-1 s-1 can be successfully synthesized via Pd-catalyzed vapor-solid-solid growth. Specifically, PdIn catalyst particles are involved and found to expose their PdIn{210} planes at the InP nucleation frontier due to their minimal lattice mismatch with nonpolar InP{2̅110} and {1̅100} planes. This appropriate lattice registration would then minimize the overall free energy and enable the highly crystalline InP NW growth epitaxially along the nonpolar directions. Because of the minimized crystal defects, the record-high electron mobility of InP NWs ( i.e., 2000 cm2 V-1 s-1 at an electron concentration of 1017 cm-3) results, being close to the theoretical limit of their bulk counterparts. Furthermore, once the top-gated device geometry is employed, the device subthreshold slopes can be impressively reduced down to 91 mV dec-1 at room temperature. In addition, these NWs exhibit a high photoresponsivity of 104 A W-1 with fast rise and decay times of 0.89 and 0.82 s, respectively, in photodetection. All these results evidently demonstrate the promise of nonpolar-oriented InP NWs for next-generation electronics and optoelectronics.

Buffer insensitive optoelectronic quality of InP-on-Si with templated liquid phase growth

As Moore's law comes to an end, the search for additional integrated circuit functionality has shifted from scaling down lateral dimensions to combining multiple materials onto a single substrate. However, the quality of crystalline semiconductors is highly sensitive to the substrate upon which it is grown, preventing multiple materials from being directly grown on single substrates. To circumvent this challenge, many complex growth strategies have been developed, such as strain relaxation buffer-layers, nanostructure growth, and template selective epitaxy. However, even with these advanced growth techniques, the growth of manufacturable crystalline materials is still limited to crystalline surfaces. Here, the authors show that using templated liquid phase (TLP) growth, single crystalline indium phosphide on Si can be grown using a variety of buffers, both crystalline and amorphous. Moreover, by performing detailed optoelectronic characterization, the authors find that the quality of the grown material not only closely matches commercial single crystalline InP wafers but is also highly insensitive to the buffer layer used. This unique feature of TLP growth could enable the next generation of crystalline material integration.

High quality InP epilayers grown on GaAs substrates using metamorphic AlGaInAs buffers by metalorganic chemical vapor deposition

Using compositionally step graded metamorphic AlGaInAs buffers with a thickness of 2.4 μm, we grow InP epilayers on GaAs substrates with miscuts of 2°, 7°, and 15° toward (111)A by metalorganic chemical vapor deposition. The InP top layer is almost strain-free and its quality depends on the substrate miscut. Strong phase separation in AlGaInAs buffers is observed in the 2° sample, while it is suppressed in 15° sample. Finally, a higher crystalline quality InP epilayer with a root-mean-square roughness of 10.1 nm is obtained on 15° substrate as confirmed by a much stronger photoluminescence peak intensity of the InP epilayer on 15° substrate compared with those on 2° and 7° substrates. Growth of high quality InP on GaAs opens up the possibility of integrating GaAs and InP based devices, and will greatly enhance the functionality of devices grown on GaAs substrates.

A single crystalline InP nanowire photodetector

Single crystalline nanowires are critical for achieving high-responsivity, high-speed, and low-noise nanoscale photodetectors. Here, we report a metal-semiconductor-metal photodetector based on a single crystalline InP nanowire. The nanowires are grown by a self-catalyzed method and exhibit stacking-fault-free zinc blende crystal structure. The nanowire exhibits a typical n-type semiconductor property and shows a low room temperature dark current of several hundred pA at moderate biases. A photoresponsivity of 6.8 A/W is obtained at a laser power density of 0.2 mW/cm2. This work demonstrates that single crystalline InP nanowires are good candidates for future optoelectronic device applications.

Wurtzite-Phased InP Micropillars Grown on Silicon with Low Surface Recombination Velocity.

The direct growth of III-V nanostructures on silicon has shown great promise in the integration of optoelectronics with silicon-based technologies. Our previous work showed that scaling up nanostructures to microsize while maintaining high quality heterogeneous integration opens a pathway toward a complete photonic integrated circuit and high-efficiency cost-effective solar cells. In this paper, we present a thorough material study of novel metastable InP micropillars monolithically grown on silicon, focusing on two enabling aspects of this technology-the stress relaxation mechanism at the heterogeneous interface and the microstructure surface quality. Aberration-corrected transmission electron microscopy studies show that InP grows directly on silicon without any amorphous layer in between. A set of periodic dislocations was found at the heterointerface, relaxing the 8% lattice mismatch between InP and Si. Single crystalline InP therefore can grow on top of the fully relaxed template, yielding high-quality micropillars with diameters expanding beyond 1 μm. An interesting power-dependence trend of carrier recombination lifetimes was captured for these InP micropillars at room temperature, for the first time for micro/nanostructures. By simply combining internal quantum efficiency with carrier lifetime, we revealed the recombination dynamics of nonradiative and radiative portions separately. A very low surface recombination velocity of 1.1 × 10(3) cm/sec was obtained. In addition, we experimentally estimated the radiative recombination B coefficient of 2.0 × 10(-10) cm(3)/sec for pure wurtzite-phased InP. These values are comparable with those obtained from InP bulk. Exceeding the limits of conventional nanowires, our InP micropillars combine the strengths of both nanostructures and bulk materials and will provide an avenue in heterogeneous integration of III-V semiconductor materials onto silicon platforms.

Single crystalline nitrogen-doped InP nanowires for low-voltage field-effect transistors and photodetectors on rigid silicon and flexible mica substrates

Doped nanowires can exhibit improved performance compared with the un-doped ones especially in conductivity. N-doped InP nanowires are synthesized by chemical vapor deposition and fabricated into field effect transistors (FETs) and photodetectors on rigid silicon, flexible mica slice and polyethylene terephthalate (PET) film. Single N-doped InP nanowire FET on silicon wafer shows excellent electrical transport property and classical n-type semiconductor behavior with a high on-off ratio of 822 and a high carrier mobility of 43.6cm2v−1s−1, which is much higher than pure InP nanowire. Single N-doped InP nanowire photodetector on silicon wafer exhibits a fast response time and a high white light responsibility of 0.19×104AW−1 at the bias voltage of 1.0V. The devices are also fabricated on flexible transparent mica slice, a novel flexible substrate and PET film, which possess perfect ductility, folding endurance and preserve high performance. Furthermore, hybrid organic–inorganic poly (3-hexylthiophene) (P3HT): N-doped InP nanowire heterojunction photodetectors are also fabricated, showing much improved photocurrent compared with the pristine N-doped InP nanowire photodetectors based on different substrates. These N-doped InP nanowire devices exhibit the low power consumption, high performance and flexibility of nano-devices, which are promising for future applications requiring large-area, high speed and low-power consumption devices.

Vapor–Solid growth of InP and Ga2O3 based composite nanowires

InP/Ga 2 O 3 core-shell nanowires were grown on Si substrate at 400 oC in the hydrazine (N 2 H 4 ) vapor diluted with 3 mol. % H 2 O. The crystalline InP and solid Ga served as source materials for the growth of nanowires. According to TEM and EDX data the nanowires consisted of wurtzite InP core with an amorphous Ga 2 O 3 shell. The minimum diameter of NWs was 14 nm, while the maximum lengths reached several micrometers. The twinned planes appeared in WZ InP core at increased nanowire diameters. Based on the obtained results and possible chemical reactions, the following mechanism was proposed for the growth of core-shell nanowires: pyrolytic decomposition of hydrazine caused the appearance of intermediate NH 2 , NH and H species in the vapor. At elevated temperatures the crystalline InP source was also dissociated to In droplets and phosphorus precursors. At source temperatures close to 600 oC, due to the interaction of In and Ga sources with water molecules and hydrazine decomposition products the volatile Ga 2 O and In 2 O were formed. These molecules reached the Si substrate which was heated to 400oC. The final chemical reaction involved Ga 2 O 3 , I 2 O 3 and phosphorus precursors. As a result of a spontaneous reaction the Ga 2 O 3 and InP phases were produced and segregated. The InP crystallized as a core while Ga 2 O 3 created the amorphous shell, because the growth temperature was insufficient for its crystallization.

Epitaxial Growth and Layer Transfer of InP through Electrochemically Etched and Annealed Porous Buried Layers

High crystalline quality InP is epitaxially grown on porous InP layers and characterized. Etching the wafers in hydrochloric acid with different concentrations and current densities create a dual layer porous structure with a more dense top layer for epitaxial growth and a buried porous layer. Annealing the structure forms voids in the buried layer. Epitaxial layers with thickness of about 2 µm were grown on dense layers. The layers grown were analyzed by transmission electron microscopy and high resolution x-ray diffraction and determined to be high quality single crystal layers. The porous samples created were bonded to PDMS substrates and the top layer was easily peeled off due to fracture through the high porosity layer. Layer transfer was also performed by gluing the samples to glass slides and pulling them apart. The transferred layers were characterized by scanning electron microscopy. These results point to the usefulness of porous III-V layers as templates for epitaxial growth and device transfer.

Evolution of periodic structures on InP (100) surface irradiated with femtosecond laser

Single crystalline InP was irradiated in air with p-polarized Ti:sapphire femtosecond laser at a fixed laser fluence of 274mJ/cm2. Ripples parallel to the laser polarization direction were found to form preferentially for small number of laser pulses ranging from 50 to 300 or at positions far from the center of laser spot, whereas grooves with the direction perpendicular to the laser polarization appeared to be superimposed on ripples for larger number of laser pulses or at positions close to the center of laser spot. Results reveal that ripple formation is a precursor for the formation of grooves and pattern evolution is dependent on the laser fluence used.

Electrodeposition of High-Purity Indium Thin Films and Its Application to Indium Phosphide Solar Cells

We report on advances in the electrochemical deposition of indium (In) on molybdenum foil that enables deposition of electronic-grade purity, continuous films with thickness in the micron range. The desired In film morphology is obtained from an InCl3 aqueous bath by using a high current density of 250 mA/cm2 and a low deposition-bath temperature of −5°C to increase the nucleation density of In islands until a continuous film is obtained. As an example application, the electrodeposited In films are phosphorized via the thin-film vapor-liquid-solid growth method. The resulting poly-crystalline InP films display excellent optoelectronic quality, comparable to single crystalline InP wafers, thus demonstrating the versatility of the developed electrochemical deposition procedure.

High-quality InP nanoneedles grown on silicon

In this letter, we report the growth of self-assembled, catalyst-free InP nanoneedles on Si substrate by low-temperature metal-organic chemical vapor deposition. With a characteristic core-shell growth mode, the nanostructure size is scalable with growth time, and InP/InGaAs/InP double-heterostructure is demonstrated. Single crystalline wurtzite InP nanoneedles essentially free of stacking faults and polytypism are achieved. The internal quantum efficiency of as-grown unpassivated InP nanoneedles can reach as high as 15% at room temperature. Laser oscillation is realized from single InP nanoneedle under optical pump. These promising results reveal the potential of integrating InP nanoneedle optoelectronic devices with traditional silicon.

InP nanocrystals on silicon for optoelectronic applications

One of the solutions enabling performance progress, which can overcome the downsizing limit in silicon technology, is the integration of different functional optoelectronic devices within a single chip. Silicon with its indirect band gap has poor optical properties, which is its main drawback. Therefore, a different material has to be used for the on-chip optical interconnections, e.g. a direct band gap III–V compound semiconductor material. In the paper we present the synthesis of single crystalline InP nanodots (NDs) on silicon using combined ion implantation and millisecond flash lamp annealing techniques. The optical and microstructural investigations reveal the growth of high-quality (100)-oriented InP nanocrystals. The current–voltage measurements confirm the formation of an n–p heterojunction between the InP NDs and silicon. The main advantage of our method is its integration with large-scale silicon technology, which allows applying it for Si-based optoelectronic devices.

Fabrication of self-masked InP nanopillars by electron cyclotron resonance ion etching

Fabrication of high quality InP nanopillar structures, with the help of self-masking properties and using the electron cyclotron resonance ion etching techniques, can be a easy demanding and one step large scale production method compared to the traditional, expensive and multi-step complicated methods. In this paper regular arrays of crystalline and high aspect ratio InP nanopillars were fabricated by low energy electron cyclotron resonance Ar+ ion irradiation technique. Several scanning electron microscopy images were utilized to investigate the width, height, and orientation of these nanopillars. The average width and length of these nano-pillars were about 50nm and 500nm, respectively. Cross-sectional high resolution transmission electron microscopy studies revealed that these nanopillars are crystalline in nature. Photoluminescence measurements also revealed the crystalline nature as well as the enhancement in PL intensity due to the large surface area of the nanopillars.

High-performance indium phosphide nanowires synthesized on amorphous substrates: from formation mechanism to optical and electrical transport measurements

InP NWs have been extensively explored for next-generation electronic and optoelectronic devices due to their excellent carrier mobility, exciton lifetime and wave-guiding characteristics. Typically, those NWs are grown epitaxially on crystalline substrates which could limit their potential applications requiring high growth yield to be printable or transferable on amorphous and flexible substrates. Here, utilizing Au as catalytic seeds, we successfully demonstrate the synthesis of crystalline, stoichiometric and dense InP NWs on amorphous substrates. Notably, the NWs are found to grow via the vapor–liquid–solid (VLS) mechanism with a narrow distribution of diameter (34.6 ± 7.7 nm) uniformly along the entire NW length (>10 μm). Although the grown NWs possess a substantial amount of twin defects, the fabricated NW FETs still exhibit impressive electrical performance with high carrier mobility (∼350 cm2 V−1 s−1) and ION/IOFF ratio (∼106). All these have demonstrated the promising potency of such NWs grown on amorphous substrates for technological applications, as compared to the conventional MBE or MOCVD grown InP NWs.

TBP를 이용한 InP 에피층의 MOVPE 성장

TBP (tertiarybutylphosphine), a relatively new material for phosphorus, has been studied with EDMIn (ethyldimethylindium) as an indium source for the growth of InP by MOVPE (metalorganic vapor phase epitaxy). Mirror smooth and good crystalline InP layers were obtained at <TEX>$500-600^{\circ}C$</TEX> with the TBP/EDMIn molar ratio as low as 21. The deposited InP layers are all n-type with the electron concentration in the range of (5-10)<TEX>${\times}10^{16}\;cm^{-3}$</TEX>, which is a lot higher than those from <TEX>$PH_3$</TEX>. This high concentration is due presumably to the high concentration of donor impurities in TBP. And it has been found that the formation of adduct occurs between EDMIn and TBP at room temperature when the partial pressure of EDMIn in the reactant mixture is above <TEX>$1{\times}10^{-2}$</TEX> Torr. The high concentration of impurities in TBP and the adduct formation between EDMIn and TBP are major obstacles in replacing <TEX>$PH_3$</TEX> and TMIn for the growth of device quality InP layers.

Large-area InP-based crystalline nanomembrane flexible photodetectors

Large-area (3×3 mm2) flexible photodetectors were realized, based on crystalline InP semiconductor nanomembranes transferred to flexible polyethylene terephthalate substrates. Very low dark current (a few microamperes) and high responsivity (0.12 A/W) were demonstrated for flexible InP p-i-n photodetectors. Bending characteristics were also investigated for this type of flexible crystalline semiconductor photodetector, and it was found that, whereas the dark current was independent of bending radii, the photocurrent degraded, depending on the bending radii.

Anisotropic vibrations in crystalline and amorphous InP

The temperature-dependent evolution of atomic vibrations in crystalline and amorphous InP has been studied using extended x-ray absorption fine-structure (EXAFS) spectroscopy. Measurements were performed at the In K edge for temperatures in the range of 20-295 K. In crystalline InP, the first nearest-neighbor (NN) EXAFS Debye-Waller factor, representative of the correlated mean-square relative displacement (MSRD) parallel to the bond direction, is considerably smaller than the uncorrelated mean-square displacement (MSD) determined from x-ray diffraction measurements. In contrast, the MSRD perpendicular to the bond direction agrees well with the MSD. This clearly demonstrates that vibrations of two neighboring atoms relative to each other are strongly reduced along the bond direction but are unhindered perpendicular to it, consistent with the well-known behavior of III-V semiconductors where bond bending is energetically favored over bond stretching. With increasing interatomic distance, the correlation of atomic motion quickly vanishes as manifested by increased EXAFS Debye-Waller factors. For the third NN shell the value closely approaches the MSD demonstrating the nearly uncorrelated motion of atoms only three shells apart. In the amorphous phase, only information about the first NN shell is accessible although the latter is now comprised of both P and In atoms. The EXAFS Debye-Waller factors are significantly higher than in the crystalline phase but exhibit a very similar temperature dependence. This results from strongly increased structural disorder in the amorphous phase whereas the thermally induced disorder is very similar to that in crystalline InP. A correlated Einstein model was fitted to the Debye-Waller factors yielding Einstein temperatures that vary as functions of the vibrational phase difference and reduced mass of the atomic pair, and represent a measure of the strength and thermal evolution of the corresponding relative vibrations.

Synthesis, characterization and photoconductivity of highly crystalline InP nanowires prepared from solid hydrogen phosphide

Download options Please wait... Supplementary files TEM images of Bi nanoparticles, SEM image of InP NWs as a matand electron diffraction pattern for growth directionanalysis PDF (2491K) Article information DOI https://doi.org/10.1039/B902474C Article type Paper Submitted 05 Feb 2009 Accepted 23 Apr 2009 First published 28 May 2009 Download Citation J. Mater. Chem., 2009,19, 4852-4856 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Synthesis, characterization and photoconductivity of highly crystalline InP nanowires prepared from solid hydrogen phosphide T. H. Lim, S. Ravi, C. W. Bumby, P. G. Etchegoin and R. D. Tilley, J. Mater. Chem., 2009, 19, 4852 DOI: 10.1039/B902474C To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author Teck H. Lim Shrividya Ravi Christopher W. Bumby Pablo G. Etchegoin Richard D. Tilley