Epitaxy Of InP Research Articles

Focused-Ion-Beam Surface Modification for Selective Growth of InP Wires and GaAs

A novel method for selective, maskless deposition of InP on GaAs has been developed. This method combines focused-ion-beam (FIB) implantation of a GaAs substrate followed by hydride vapor phase epitaxy (VPE) of InP. The dependence of the selective growth mechanism on ion mass and dose is explored, and its cause is sought by examining the implanted surface with an atomic-force microscope (AFM). Since InP forms a single crystal with few defects, this new selective-epitaxy technique shows great promise for applications in quantum device fabrication.

Spectroscopic ellipsometry: a useful tool to determine the refractive indices and interfaces of In 0.52Al 0.48As and In 0.53Al xGa 0.47 - xAs on InP in the wavelength range from 280 to 1900 nm

The refractive indices of layers of the quaternary materials In 0.53Al 0.21Ga 0.26As and In 0.53Al 0.31Ga 0.16As on InP are measured for the first time by spectroscopic ellipsometry in the wavelength range from 280 to 1900 nm. In previous papers we found out that between InP and molecular beam epitaxy (MBE) grown In 0.52Al 0.48As, In 0.53Al 0.405-Ga 0.065As, In 0.53Al 0.11Ga 0.36As, and In 0.53Ga 0.47As layers an interface layer exists, owing to the exchange of phosphorus and arsenic atoms during the As 4-stabilized oxide desorption procedure before the MBE growth. We investigated two layers (with different thicknesses) of each composition for the determination of the refractive indices and the exact values of the thicknesses.

Kinetic surface roughening in molecular beam epitaxy of InP.

Surface roughening of (100) InP films grown by metalorganic molecular beam epitaxy was observed by scanning force microscopy. The roughening process gives rise to periodic elongated terraces aligned in the [01\ifmmode\bar\else\textasciimacron\fi{}1] direction; kinetic control by surface diffusion activation is indicated by the dependence on group III and V fluxes, and growth temperature. Below a given temperature for each set of growth parameters the surface roughness shows two distinct power law regimes dependent on the film thickness. This result supports growth models using ballistic aggregation and surface diffusion.

High-resolution x-ray diffraction to determine the self-limiting growth in atomic layer epitaxy of InP and InAs/InP heterostructures

High-resolution x-ray diffraction (HRXRD) can be used to quickly and precisely evaluate the self-limiting growth of atomic layer epitaxy (ALE) of III-V compounds and heterostructures. We have studied atomic layer epitaxy of InP and InAs/InP heterostructures in a conventional low pressure metalorganic vapor phase epitaxy reactor. We used the interference of x-ray wave fields in the grown structures to measure nondestructively the thickness of the deposited film with relatively high precision. A self-limiting growth close to 1 monolayer/cycle has been obtained for InP and InAs with a substrate temperature as low as 350–360 °C. HRXRD and photoluminescence measurements have demonstrated the structural and optical high quality of ALE-grown InP and InAs/InP heterostructures.

Electrical and optical properties of InP grown by metalorganic vapor phase epitaxy with extremely low V/III ratios using tertiarybutylphosphine

Metalorganic vapor phase epitaxy of InP with extremely low V/III ratios less than 10 was successfully carried out by using tertiarybutylphosphine, and detailed electrical and optical properties were investigated for the first time. Featureless surface morphology was obtained even with a V/III ratio of as low as 3. Good electrical properties, such as carrier concentrations of about 6×1014 cm−3 and electron Hall mobilities more than 30 000 cm2/V s measured at 77 K were confirmed, although both Van der Pauw and low-temperature photoluminescence results proved the increased acceptor concentrations in the low V/III ratio range.

Molecular Beam Epitaxy and Migration-Enhanced Epitaxial Growth of InP Using Polycrystalline InP as Phosphorus Source

InP was grown by means of molecular beam epitaxy (MBE) and migration-enhanced epitaxy (MEE) using polycrystalline InP as the phosphorus source. Pregrowth thermal cleaning of the InP substrate was performed under either P2-beam or As4-beam irradiation. It is shown that polycrystalline InP is a highly controllable and useful source of a P2 beam for MBE and MEE growth of high-quality InP in the standard MBE system. The As4 cleaning was found to be more controllable and reproducible than the P2 cleaning. Although the As4 cleaning produced an ultrathin InAs interface layer, no inclusion of As was detected and no influence was found on the crystalline and electrical properties of the epilayer. Unintentionally doped layers showed n-type conduction with carrier concentration in the range of 5×1016-1×1018 cm-3, showing a remarkable dependence on the growth temperature.

Facet growth in selective area epitaxy of Inp by MOMBE

InP facet growth near SiO 2 mask edges during metalorganic molecular beam epitaxy is studied for various V/III ratios on (100) substrates with 2° misorientation towards (110). While ideal vertical layer growth occurs at high V/III ratio even up to 2 μm growth thickness, oblique (111) planes are kinetically favoured near mask edges at lower V/III ratio. The V/III ratio is a key parameter since it determines the facets with the lowest kinetically limited growth rate at the border of the growing layer. Also the diffusion length of mobile adsorbed species, by which additional features near mask edges and corners are explained, decreases with V/III ratio. Besides interfacet diffusion driven by concentration gradients between facets of different growth rate, there is evidence also for anisotropic diffusion along [0–1] on (100) InP. We speculate that this is the origin of the fine surface ripples on InP surfaces observed on one side near the SiO 2 masks.

Current status of selective area epitaxy by OMCVD

In this paper we review the current status of the achievements and understanding of selective area epitaxy using organometallic chemical vapor deposition (OMCVD) in the conventional mode, atomic layer epitaxy mode, and photon assisted growth mode. The selective epitaxy of GaAs, AlGaAs, and InP can be readily achieved. However, the selective epitaxy of compounds such as GaInAs has proven to be difficult due to a large compositional deviation. In addition, the control of the lateral thickness profile and facets at the edges has proven to be difficult for both binaries and their alloys. Selective epitaxy has been used to fabricate a variety of electronic and optoelectronic devices and low-dimensional structures. While considerable progress has been made, a better understanding of the processes is necessary before they can be applied to large scale optoelectronic integration.

Characterization of InP grown by low-pressure MOVPE using ethyldimethylindium and tertiarybutylphosphine

A new source material combination of ethyldimethylindium (EDMIn) and tertiarybutylphosphine (TBP) is used for low-pressure metalorganic vapor phase epitaxy (MOVPE) of InP. The growth rate dependence on the V/III ratios indicates that a EDMIn:TBP parasitic reaction exists. However, InP layers grown using EDMIn and TBP show good electrical and optical properties, comparable to those using a conventional source material combination of trimethylindium (TMI) and phosphine (PH 3). The highest electron mobility at 77 K is 56,000 cm 2/V · s with a free carrier concentration of 1.0 × 10 15 cm -3. Sharp and well resolved exciton peaks were observed in 4.0 K PL spectra.

Migration-Enhanced Epitaxy of InP Using Polycrystalline InP as Phosphorus Source

InP was successfully grown by the migration-enhanced epitaxy (MEE) mode using polycrystalline InP as the phosphorus source in a conventional GaAs-type molecular beam epitaxy (MBE) chamber. A long and persistent reflection high-energy electron diffraction (RHEED) oscillation was observed. (2×4) RHEED patterns were observed in both In-supply and P2-supply periods, being different from the GaAs MEE growth. Compared with the conventional MBE, the MEE growth afforded epitaxial layers of better surface morphology and greatly improved photoluminescence properties.

High quality InP and In 1−xGa xAs yP 1−y grown by gas source MBE

The growth of high quality InP and In 1−xGa xAs yP 1−y by gas source molecular beam epitaxy is reported. 77 K mobilities up to 112,000 cm 2/V⋯s for high purity InP have been measured. Fe-doped semi-insulating InP has been grown using an iron effusion dell, and resistivities as high as 10 9 Ω cm have been obtained. Selective epitaxy of InP on Si 3N 4-patterned substrates is also presented.

Kinetic study of metalorganic molecular beam epitaxy of GaP, InP, and GaxIn1−xP

The growth rates of GaP and InP deposited by metalorganic molecular beam epitaxy using triethylgallium, trimethylindium, and precracked phosphine have been studied by reflection high energy electron diffraction and related to composition variations of the ternary alloy GaxIn1−xP. The influence of the substrate temperature and phosphine flow rate have been investigated for each material. The GaP growth rate dependence with temperature exhibits qualitatively the same behavior as already reported for the growth of GaAs by metalorganic molecular beam epitaxy. In the case of InP, a constant growth rate is observed in the temperature range of 450–500 °C. At higher temperatures, a strong decrease of the growth rate, attributed to the desorption of dimethylindium species, is measured. Meanwhile, the GaxIn1−xP composition is found to become Ga rich while increasing temperature. Furthermore, it is found to significantly depend on the phosphine flow rate at a fixed temperature. In the low phosphine flow regime, the composition is associated with the preferential formation of GaP bonds, and in the high phosphine flow regime, the composition is closely correlated with the sharp decrease observed for the binary InP growth rate.

Diffusion of Zn acceptors during MOVPE of InP

The unintentional diffusion of Zn acceptors was investigated during low pressure metalorganic vapour phase epitaxy (MOVPE) of InP at 550 and 640°C using trimethylindium (TMIn), phosphine (PH 3) and diethylic (DEZ) precursors. Comparison of hole concentrations obtained with a polaron etch profiler with Zn profiles obtained by secondary ion mass spectroscopy (SIMS) indicate a low level of compensation, i.e. a small ratio of interstitials to substitutionals. The data fit a model where diffusion takes place via Zn interstitials. The small concentration of these interstitials in samples doped during growth explains the lower (by 2 to 3 orders of magnitude) diffusion constant compared to that observed during intentional doping by indiffusion.

Transient behavior in RHEED intensity oscillations observed in chemical beam epitaxy of InP

Detailed observations have been made of the reflection high-energy electron diffraction (RHEED) intensity oscillations immediately after the initiation of the growth of InP by chemical beam epitaxy (CBE). The oscillation periods for the first several cycles were shorter than those for the succeeding steady state cycles. The oscillation period approached asymptotically to the steady state period. In the initial few cycles, one period does not correspond to one monolayer growth. It was found that the transient behavior is substantially associated with the increase of average step density on the growing surface.

Mg incorporation process during LP-MOVPE of InP, GaInAs and GaInAsP

The Mg incorporation process has been studied during low pressure metalorganic vapor phase epitaxy of InP, GaInAs and GaInAsP layers. In InP a cubic increase of the carrier concentration versus Mg flow in the gas phase is observed; a maximum carrier concentration of 2 × 10 18 cm −3 can be obtained. Results from Hall measurements and low temperature photoluminescence suggest that above a critical level of 10 18 atoms/cm 3 Mg is incorporated in InP both as a substitutional acceptor and as an interstitial donor. In ternary layers and in quaternary layers with a rather high Ga content the carrier concentration exhibits a square increase versus Mg flow; a saturation at a level of approximately 1 × 10 19 cm -3 is reached. The data can be explained assuming that in Ga containing compounds, such as ternary and quaternary layers, the concentration of interstitial Mg is much lower than in InP leading to a markedly reduced Mg diffusion during growth even at high concentrations.

Mev Ion Beam Applications In III-V Semiconductors

ABSTRACTThis paper reviews some key areas where MeV ion beams can be applied to III-V semiconductor materials. In particular, ion damage is assessed for various III-V materials in terms of implantation parameters, especially substrate temperature and dose rate. Implant isolation, involving the introduction of damage to remove carriers and achieve highlyresistive layers, is assessed for MeV irradiation. It is concluded that MeV ions can provide deep, uniform damage with a single-energy implant. Finally, improved epitaxy of amorphous InP with MeV ions is demonstrated.

Mg diffusion during metalorganic vapor phase epitaxy of InP

The diffusion mechanism of Mg has been studied during low-pressure metalorganic vapor phase epitaxy of InP. The Mg dopant profiles were measured by secondary-ion mass spectroscopy. The analysis reveals that abrupt Mg dopant profiles are possible; the Mg diffusion, however, strongly depends on the Mg concentration in the crystal lattice. Simultaneous doping with Si leads to a distinct decrease of the Mg diffusion. This behavior is consistent with a model assuming that Mg diffuses as a complex involving a deep donor.

Epitaxial nucleation and growth kinetics of indium phosphide in an InPH 3HClH 2 system

The epitaxial nucleation and growth kinetics of InP deposition in an InPH 3HClH 2 system have been discussed. The classical theory of heterogeneous nucleation has been used to analyse the initial stages of InP epitaxy on the surface of the crystalline substrate and the effect of substrate orientation on the nucleation behaviour of InP has been explained. A kinetic model which includes a scheme of reactions has been developed for the deposition of InP with reaction constants and hence the growth rate of epitaxial InP has been investigated. The effects of various experimental parameters on the growth rate have been discussed.

Observations on intensity oscillations in reflection high-energy electron diffraction during gas source molecular beam epitaxy of InP

We report the first observation of reflection high-energy electron diffraction intensity oscillations during the growth of InP using trimethylindium and phosphine in gas source molecular beam epitaxy (GSMBE). By optimizing the growth conditions, intensity oscillations more than 700 periods have been observed. The temperature and flux dependence of the oscillating behavior have been studied. Results indicate that the growth of InP by GSMBE is predominantly via a two-dimensional layer-by-layer mode.

Doping of InP and GaInAs during organometallic vapor-phase epitaxy using disilane

Disilane (Si2H6) is presented as a new silicon doping source in the organometallic vapor-phase epitaxy of InP and GaInAs. The doping characteristics of disilane were studied under a range of growth conditions used to obtain device quality layers. Silicon incorporation by means of disilane shows a different behavior in InP and GaInAs doping. The slope of the log N vs log (disilane flow) plot is 0.75 for InP and 1 for GaInAs. A variation of doping level with growth temperature was observed revealing an activation energy of 1.2 eV in the case of InP. Electrical measurements on disilane-doped InP and GaInAs yield the same high mobilities as obtained in otherwise doped films, indicative of low compensation.