Fe-doped InP Substrates Research Articles

Investigation of Comet-Shaped Defects in an EPI-InP Layer Grown on S-Doped and Fe-Doped InP Substrates

Investigation of Comet-Shaped Defects in an EPI-InP Layer Grown on S-Doped and Fe-Doped InP Substrates

Suppressing twin formation in Bi2Se3thin films

The goal of the present work was to reveal the origin of the formation of different structural defects in Bi2Se3 thin films. We conducted a detailed comparative study of layers grown on InP(111)A and -B terminated flat and rough substrates using reflection high-energy electron diffraction (RHEED), atomic force microscopy (AFM), X-ray reflectivity (XRR), X-ray diffraction (XRD) and probe-corrected scanning transmission electron microscopy (STEM). This choice of substrate reduces the formation of mosaicity twist sufficiently due to an almost perfect lattice match (0.2%) between InP and Bi2Se3. The use of substrates with different terminations and roughnesses allows the factors that define twin formation to be identified, providing conclusions about how twinning can be controlled and suppressed. In particular we have shown that growth using molecular beam epitaxy on rough Fe-doped InP(111) substrates leads to the formation of high quality thin films, with very low mosaicity twist and with complete suppression of twins in the Bi2Se3 thin films. No extra layer was observed at the interface between the film and the substrate. We also showed that the substrate surface termination (A or B) defines which family of twin domains dominates. The only types of structural defects that remain in the films are antiphase grain boundaries associated with the variation in substrate height. We believe that our study is relevant not only for Bi2Se3 growth but that it also provides essential insight for obtaining monocrystalline A2B3 (A = Bi, Sb; B = Se, Te) chalcogenide thin films and for realizing desirable electrical properties within this class of materials.

Microstructural characterisation of Bi2Se3 thin films

The microstructure of Bi2Se3 thin films grown by molecular beam epitaxy on Si(111), InP(111)B and Fe-doped InP(111)B substrates has been studied in detail using scanning transmission electron microscopy. Films grown on Si(111) and InP(111)B substrates show the formation of twin domains: rotation twins (with the grain boundary perpendicular to the substrate) and lamellar twins (with the grain boundary parallel to the substrate). The presence of twins was confirmed by atomic-force microscopy (AFM) and X-ray diffraction (XRD). At the interface between Bi2Se3 film and Si(111) or InP(111)B substrates poorly crystallized layers of about 1 nm and 1.8 nm thickness, respectively, followed by well-crystallized Bi2Se3 layers, were found. The use of a Fe-doped InP (111) substrate with a rough surface enables the suppression of twin formation.

利用In0.82Ga0.18As与InP衬底之间的应力制作结构材料的缓冲层

In0.82Ga0.18As layers were grown on semi-insulating Fe-doped InP(100) substrates by low pressure metalorganic chemical vapor deposition(LP-MOCVD).The growth was performed using TMIn,TMGa,and AsH3 as growth precursors of In,Ga,and As,respectively,in a horizontal reactor.The substrate on a graphite susceptor was heated by inductively coupling radio frequency power,the growth temperature was detected by a thermocouple,and the reactor pressure was kept at 1×104 Pa.Thickness of In0.82Ga0.18As layer for all samples was kept to be 300 nm.In our experiments,the growth temperature of In0.82Ga0.18As layers was 390,410,430,450,470,530 ℃,respectively.Because the strain caused by the lattice mismatch between In0.82-Ga0.18As layer and InP substrate was varied from the growth temperature,the surface of In0.82Ga0.18As layer was different.It was analyzed that the growth temperature of In0.82Ga0.18As layer influenced on the surface morphology,crystalline quality and the electrical property of the In0.82Ga0.18As layer.The surface morphology of In0.82Ga0.18As layer was studied by the scanning electron microscopy(SEM).The components and crystalline quality of In0.82Ga0.18As layer were characterized by X-ray diffraction(XRD).The electrical property of In0.82Ga0.18As layer was measured using the Hall Effect.This work shows a useful way how to design for the optimum buffer in growthing highly mismatched epitaxy layers.

Diode-pumped passively mode-locked 1342 nm Nd:YVO_4 laser with an AlGaInAs quantum-well saturable absorber

We demonstrate what we believe to be the first use of AlGaInAs quantum wells (QWs) as a saturable absorber for a diode-pumped passively mode locked Nd:YVO(4) laser at 1342 nm. The QWs are grown on a Fe-doped InP substrate that is transparent at lasing wavelength. At an incident pump power of 13.5 W an average output power of 1.05 W with a continuous mode-locked pulse duration of 26.4 ps at a repetition rate of 152 MHz was generated.

Transition to insulating behavior in the metal-semiconductor digital composite ErAs:InGaAs

Superlattice structures of semimetallic ErAs particles embedded in an InGaAs matrix were fabricated on (001) Fe doped InP substrates with varying amounts of ErAs. The samples were characterized by temperature dependent Hall measurements, x-ray diffraction, and transmission electron microscopy. The temperature dependence of the mobility, charge density, and sheet resistance is presented. The apparent offset between the conduction band minimum of the InGaAs matrix and the Fermi energy of the ErAs particles is strongly dependent on the amount of ErAs deposited. The offset is determined from the measured charge density and the InGaAs density of states. As the size of the ErAs particles increases, the Fermi level decreases from ∼0.01 eV above the InGaAs conduction band edge to ∼0.15 eV below the InGaAs conduction band edge and the electrical conduction properties change from metallic to semiconducting.

Electronic structure and conduction in a metal–semiconductor digital composite: ErAs:InGaAs

We have grown epitaxial superlattice structures of layers of semimetallic ErAs particles embedded in an InGaAs matrix on (001) Fe-doped InP substrates. Temperature-dependent Hall measurements, x-ray diffraction, and transmission electron microscopy were performed on the materials. The carrier mobility and the temperature dependence of the charge density imply conduction in the InGaAs matrix. We calculate an offset between the conduction-band minimum of the InGaAs matrix and the Fermi level of the ErAs particles that is strongly dependent on the amount of ErAs deposited. As the size of the ErAs particles increases, the Fermi level decreases from ∼0.01 eV above the InGaAs conduction-band edge to ∼0.2 eV below the InGaAs conduction-band edge and the electrical conduction properties change from metallic to semiconducting.

MOVPE Growth and Characterization of AlInAsSb/GaInAsSb multiple-quantum-well structure

We have grown unstrained Al0.66In0.33As0.85Sb0.15/Ga0.64In0.36As0.84Sb0.16 multiple-quantum-well structure on Fe-doped InP substrate by metalorganic vapor phase epitaxy. Double crystal X-ray diffraction, secondary ion mass spectrometry, and low-temperature photoluminescence were used to characterize the multiple-quantum-well structure.

GaInAsSb/InP multiple-quantum-well structure grown by metalorganic vapor-phase epitaxy

Unstrained Ga 0.64In 0.36As 0.84Sb 0.16/InP multiple-quantum-well (MQW) structure was grown on Fe-doped InP substrate by metalorganic vapor-phase epitaxy. Double-crystal X-ray diffraction (DCXRD) and transmission electron microscopy (TEM) were used for material evaluation and layer thickness determination. We observed sharp and intensive satellite peaks in the X-ray rocking curve. In the TEM micrograph, reproducible periodicity with uniform well thickness and abrupt interface could be clearly seen. The layer widths measured from DCXRD and TEM are in good agreement with the value estimated from the product of growth rate and time. Low-temperature (8 K) photoluminescence spectroscopy and room-temperature absorption spectroscopy were also used to characterize the MQW structure. The full-width at half-maximum of the (8 K) photoluminescence was 13.4 meV for the MQW structure, which is smaller than that of the GaInAsSb bulk layer. Heavy- and light-hole excitons were observed in the room-temperature absorption spectrum, which demonstrates that high-quality epilayer can be obtained for this system.

Growth of InAsP/InP quantum wells by solid source MBE on misoriented and exact InP (1 1 1)B: substrate temperature and arsenic species effects

Two series of strained InAsP/InP multiquantum wells (MQWs) were grown by solid source molecular beam epitaxy (SSMBE) simultaneously on Fe-doped InP substrates with a growth orientation of either (1 0 0), exact (1 1 1)B, and (1 1 1)B misoriented 1° toward 〈−2 1 1〉. The MQWs were grown using either dimer or tetramer arsenic (As 2 or As 4) over a substrate temperature range of 420–535°C. The θ–2 θ X-ray diffraction measurements, the atomic force microscopy (AFM) images of the surfaces, and the 8 K photoluminescence (PL) full-width at half-maximum (FWHM) values of the (1 1 1)B samples showed general improvement in the samples' material properties with increasing substrate temperature. While the X-ray diffraction measurements and the AFM images showed little difference between As 2 and As 4, the 8 K PL FWHM values varied greatly with respect to the arsenic species used. The exact (1 1 1)B samples had narrower 8 K PL FWHM values when grown with As 2. For growth on misoriented (1 1 1)B InP, the 8 K FWHM values narrowed with As 4. The misoriented (1 1 1)B samples had the narrowest 8 K PL FWHM when grown with As 4 at a temperature of 520°C; the exact (1 1 1)B at 495°C when grown with As 2.

Liquid phase epitaxial growth of InGaAs on InP using rare-earth-treated melts

High-quality In0.53Ga0.47As epilayers have been grown on semi-insulating (100) Fe-doped InP substrates. The growths were performed by liquid phase epitaxy (LPE) using rare-earth-doped melts in a graphite boat. The rare-earth elements studied were Yb, Gd and Er which act as gettering agents of impurities. Hall measurements show an elevated electron mobility for rare-earth-treated samples over undoped samples, μe=11 470 cm2/V s at 300 K and reduced carrier concentration (n-type), 9.33×1013 cm−3. The Hall results indicate an improvement in layer quality, but suggests that the treated layers are compensated. Photoluminescence (PL) studies show that the layers grown from rare-earth-doped melts have higher integrated PL efficiency with narrower PL linewidths than the undoped melt growths. The grown materials were fully characterized by Fourier transform infrared spectroscopy, double-crystal x-ray diffraction, energy dispersive spectroscopy, secondary-ion-mass spectroscopy, and deep level transient spectroscopy (DLTS). Compositional measurements reveal no measurable incorporation of rare-earth elements into the grown epilayers. DLTS measurements indicate the creation of two deep levels with rare-earth treatment, which is attributed to either the rare earth elements or impurities from within the rare-earth elements. Subsequent glow discharge mass spectrometry measurements reveal many impurities within the rare-earth elements which preferentially might lead to p-type doping centers and/or deep levels. Thus, rare-earth doping of LPE melts clearly improves epitaxial layer quality, however, the purity of commercially available rare-earth elements hinders optimal results.

The influence of annealing on the interface properties of low-dose Si implanted n-layers in semi-insulating InP

Differential Hall measurement and secondary ion mass spectrometry have been used to characterize the influences of room temperature Si implantation and annealing on the electrical properties of n-layers formed by direct implantation into liquid-encapsulated-Czochralski grown, Fe-doped InP substrates. The Si activation is affected by the background Fe level. The anneal-time influenced the electron mobility near the channel-substrate interface. Mobility degradation at the interface, present with customary anneal, could be avoided using long time anneal. The mobility changes have been correlated with the changes in the Fe distribution near the interface. The customary anneal-time introduced an Fe accumulation behind Rm, the maximum of the Si profile, followed by an Fe depletion. However, after long time anneals an Fe depletion was created between the Rm and Rm+2dRp of the Si profile and the Fe accumulation shifted behind Rm+2dRp.

Raman investigation of the photocarrier properties in both undoped and Fe-doped InP substrates

Electron-hole pairs, optically excited in the continuous regime, were studied in both nominally undoped and Fe-doped InP substrates using the Raman technique. Different results were obtained depending on whether the material was Fe doped or not. Undoped samples show a pronounced phonon-plasmon coupling effect, whereas Fe-doped specimens do not reveal such behaviour. From modelling, the stationary photocarrier concentration is evaluated as a function of critical parameters such as lifetime, surface recombination velocity or atomic Fe concentration. By comparison with data obtained under different illumination conditions, it is concluded that undoped (n-type) InP is characterized by a rather low surface recombination velocity ( S < 10 4 cm s −1 ) and a (bulk) pair lifetime of several tens of nanoseconds. In contrast, for Fe-doped (semi-insulating) material the pair lifetime is found to be lower than 1 ns, while the photocarrier density is shown to depend on the Fe concentration with a critical value arouund a few 10 16 cm −3.

A monolithic 5 Gb/s p-i-n/HBT integrated photoreceiver circuit realized from chemical beam epitaxial material

The authors report on a high performance monolithic photoreceiver fabricated from chemical beam epitaxy (CBE) grown InP/InGaAs heterostructures, incorporating a p-i-n photodetector followed by a transimpedance preamplifier circuit configured from heterojunction bipolar transistors (HBTs). The optoelectronic integrated circuit (OEIC) was fabricated on a semi-insulating Fe-doped InP substrate. Microwave on-wafer measurements of the frequency response of the transistors yielded unity current gain cutoff frequencies of 32 GHz and maximum oscillation frequencies of 28 GHz for collector currents between 2 and 5 mA. The photoreceiver was operated up to 5 Gb/s, at which bit rate a sensitivity of -18.8 dBm was measured at a wavelength of 1.5 mu m. The results demonstrate that the CBE growth technique is suitable for high performance HBT-based OEICs.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

High indium content graded channel GainAs/AlinAs pseudomorphic MODFETs

We report on the electrical and microstructural properties of InP/GaxIn1-xAs/Al0.48In0.52As modulation doped layers having compositionally graded active channels with different channel thicknesses. The layers were grown by solid source molecular beam epitaxy on Fe-doped InP substrates. The undoped GaInAs two dimensional electron gas channel layers were grown having indium compositions graded fromx = 0.53 at the substrate buffer tox= 0.65 at the heterointerface by varying the Ga cell temperature during growth. Active channel thicknesses of 20 nm and 30 nm were compared with lattice matched layers. Transmission electron microscope image analysis indicates no misfit dislocations in these structures. Hall-effect measurements at 300 K show an increase in the mobility from 8,380 cm2/Vs for the lattice matched layer to 12,500 cm2/Vs for the 30 nm pseudomorphic layer. Small gate-length, 0.25 μn, MODFETs were fabricated to determine effective velocity values from transconductance (gm) and current gain (h21) measurements. The peak dc extrinsicgm increased from 367 mS/mm for the lattice matched layer to 668 mS/mm for the 30 nm pseudomorphic layer. The effective electron carrier velocity increased from 1.57 × 107 cm/s for the lattice matched layer to 1.88 × 107 cm/s for the 30 nm pseudomorphic layer. Our results show that compositional grading is a useful technique to obtain thick pseudomorphic layers with good transport properties.

Interfacial traps in Ga0.47In0.53As/InP heterostructures

This paper reports on a study of n-type GaInAs layers grown by molecular-beam epitaxy on semi-insulating Fe-doped InP substrates. Hall measurements are performed on bevelled layers to obtain carrier concentration and mobility profiles. An infrared transient spectroscopy technique (backgating effect induced by infrared illumination in the 0.8–2 μm wavelength range) is used to detect the deep level responsible for the reduction of both carrier concentration and mobility near the heterointerface. An electronlike trap with an activation energy of ≊0.32 eV is found. Optical ionization and neutralization energies are also obtained. The results are compared with those obtained by others from electron paramagnetic resonance, photoconductivity, and deep level transient spectroscopy measurements. It is concluded that the electronlike trap, tentatively ascribed to an Fe acceptor level, is located at the heterointerface.

Selective etch-back and growth of InGaAs ON (100) Fe:lnP by electroepitaxy

Selective etch-back prior to growth of InGaAs islands on SiO2-masked (100)Fe-doped InP substrates was performed by electroepitaxy. The etch-back of the substrate and the growth of the layer was done at a constant furnace temperature of 640° C by passing a direct electric current from the melt to the substrate for etch-back and from the substrate to the melt for growth. The current density used was 1 to 20 A/cm2 for a period from 15 to 60 min. The isolated InP regions were of various sizes (40 × 1000μm to 3000 × 3000μm), and different geometries (narrow and wide strips, square, circular). A uniform etch-back and uniform growth with excellent surface morphology was obtained on strips as wide as 200μm and on circles withd {100} > {011} > {111} B > {111} A.

Evaluation of Large Diameter InP Substrate Material

AbstractExpanding interest in large-scale fabrication of electronic and photonic devices and in the scale-up of epitoxial growth reactors is creating the need for high quality large diameter InP substrate material. This paper will discuss the evaluating of three-inch diameter semi-insulating Fe-doped InP substrate material purchased from two commercial suppliers. The results of Photon Back Scatter, Infrared Transmission Microscopy, Hall Effect, and Spatially Resolved Photoluminescence measurements will be presented and evaluated.

Noise performance of submicrometer AlInAs-GaInAs HEMTs

Record DC and RF performance of AlInAs-GaInAs lattice matched to InP HEMTs (high-electron-mobility transistors) with nominally 0.2- and 0.1- mu m gate lengths have been achieved. The devices were fabricated on material grown by MBE (molecular-beam epitaxy) on Fe-doped InP substrates. The epitaxial layers consisted of an undoped AlInAs spacer, a highly doped AlInAs donor layer, an undoped Schottky-enhancing AlInAs layer, and, finally, a highly doped GaInAs layer contact layer. 50- mu m-wide devices with 0.2- and 0.1- mu m-long T-gates were fabricated. The 0.2- mu m gate-length devices were tested at V-band. The single-stage amplifier (waveguide to waveguide with no correction) exhibited a minimum noise figure F/sub min/ of 1.8 dB with an associated gain 7.5 dB at 63.0 GHz. This translates to an amplifier noise measure of 2.10 dB. The corresponding device performance was a minimum noise figure of 1.4 dB with an associated gain of 8.5 dB. This corresponds to a device noise measure of 1.6 dB.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Electronic properties of [formula omitted] strained-layer superlattices prepared by hydride vapor phase epitaxy

InAs x P 1− x InAs superlattices with 0.63 ≤ × ≤ 0.83 have been grown by hydride vapor phase epitaxy on semi-insulating Fe-doped InP(100) substrates using a single barrel horizontal reactor. The superlattices consisted of 60–150 layers of alternate InAsP and InAs with an individual layer thickness in the range of 200–500 Å. The net carrier concentrations for these structures at 295 K are in the low 10 16 cm −3 range with electron mobilities between 8,130 and 12,100 cm 2/(V − sec.). The highest electron mobility was obtained for an InAs 0.7 P 0.3 InAs superlattice, which has a lattice misfit strain of 0.95%. The highest 77 K mobility observed for the InAsP/InAs structures was 4.7 × 10 4 cm 2/V − sec.) for a net carrier concentration of 1.15 × 10 16 cm −3. Electronic conduction mechanisms in the superlattices were studied from their magnetotransport properties at 1.6 K. Highly anisotropic magnetoresistance was noted for magnetic fields perpendicular and parallel to the layers. For low fields a negative magnetoresistance that was proportional to the square of the magnetic field was observed. For samples with high electron mobility, oscillations in the magnetoresistance were noted at high magnetic fields.