Pressure Organometallic Vapor Phase Epitaxy Research Articles

Photo-and electroluminescence of ZnSe grown by OMVPE

Undoped ZnSe epilayers have grown on (100) GaAs substrates by atmospheric pressure organometallic vapor phase epitaxy (OMVPE) with dimethylzinc (DMZ) and hydrogen selenide (H 2Se) as source. The epilayers grown under 270–325°C exhibit low resistivity of about 1Ω·cm. The carrier concentration and mobility are of the order of 10 16cm -3 and 300–400 cm 2.v -1.s -1 respectively at RT. A strong NBE emission of PL and EL spectra are observed at 77K and RT respectively.

Atomic steps at GaInAs/InP interfaces grown by organometallic vapor phase epitaxy

InP/GaInAs/InP quantum well structures have been grown using atmospheric pressure organometallic vapor phase epitaxy (OMVPE). For thin wells the 10 K photoluminescence spectra show a clearly resolved doublet (or in some cases a triplet). The energy separation of the two peaks increase with decreasing well width down to a nominal width of approximately two to three atomic monolayers. For thinner wells the energy separation decreases with decreasing well width. The doublet is interpreted as being due to the photoluminescence from two wells differing in thickness by a single monolayer. A simple calculation for a finite quantum well describes the general features of the energy splitting versus well width. The half-widths of the two photoluminescence peaks for the thin wells, where the two peaks are resolved, are extremely narrow. The value of <15 meV for the thinnest well is much better than observed previously for low-pressure or atmospheric-pressure OMVPE and matches the results obtained by chemical beam epitaxy.

Use of tertiarybutylphosphine for the growth of InP and GaAs1-xPx

A newly-developed phosphorus source, tertiarybutylphosphine (TBP), which is much less toxic than PH3, has been used to grow InP and GaAs1-xPx by atmospheric pressure organometallic vapor phase epitaxy (OMVPE). Excellent morphologies are obtained for the growth of InP between 560 and 630° C for TBP partial pressures larger than 0.5 x 10-3. For the first time, V/III ratios as low as 3 have been used to grow InP epilayers with featureless morphologies at 600° C. To obtain good morphologies at both lower and higher temperatures, higher TBP partial pressures are necessary. The electron mobility increases and the electron density decreases as the temperature is increased. The highest room temperature mobilities and lowest electron densities, obtained at 630° C, are 3800 cm2/V-sec and 3 x 1015 cm-3, respectively. The 10 K photoluminescence spectra of the InP epilayers at higher growth temperatures show no carbon contamination. Bound excition half widths as low as 3.0 meV have been measured. The use of TBP to replace PH3 in the growth of GaAs1-xPx results in a nearly linear relationship between vapor and solid composition at 610° C,i.e., the P distribution coefficient is nearly unity. This contrasts sharply with the very low P distribution coefficient obtained using PH3 at such low growth temperatures.

Structural and photoluminescent properties of GaInAs quantum wells with InP barriers grown by organometallic vapor phase epitaxy

Ga0.47In.53As/InP quantum well structures grown by atmospheric pressure organometallic vapor phase epitaxy are characterized by high-resolution transmission electron microscopy (HRTEM) and 4 K photoluminescence (PL). Microdensitometer analysis of the HRTEM images shows GaInAs wells as narrow as 10 Å with slightly asymmetric interface widths. The InP to GaInAs transitions occur within 200 monolayers while the GaInAs to InP transitions are 3–5 monolayers wide, probably due to As carryover. 4 K PL shows half-widths below 9 meV for quantization shifts up to 140 meV. PL peak shifts as large as 395 meV for the narrowest quantum wells are observed compared to bulk Ga0.47In0.53As.

A front-side-illuminated InP/GaInAs/InP p-i-n photodiode with a —3-dB bandwidth in excess of 18GHz

High-speed front-side illuminated InP/GaInAs / InP p-i-n 1-1.6-µm photodetectors have been fabricated from materials grown by atmospheric pressure organometallic vapor phase epitaxy (OMVPE). The AR-coated devices have external quantum efficiencies of > 85 percent at 1.3 µm and the temporal response has a full-width half-maximum (FWHM) of < 18 ps. Dark current density is 6 × 10-6A . cm-2at an operating bias of -4 V. The interface is abrupt to two monolayers at the InP (substrate)-GaInAs heterojunction and five monolayers at the GaInAs-InP p-layer heterojunction.

Doping superlattices in GaP

Atmospheric pressure organometallic vapor-phase epitaxy was used to grow GaP doping superlattices. Measurements are reported for the first doping superlattice with a band gap which is indirect in both real space and k space. The first observations of phonon replicas in a n-i-p-i photoluminescence (PL) spectrum and a n-i-p-i-like PL peak coming from donor–acceptor transitions are also reported. Large energy shifts of 60 meV per decade of excitation intensity have been observed. The n-i-p-i peak intensities increased linearly with excitation intensity, and the bound exciton peak intensities increased superlinearly, at low illumination intensity, as expected for a periodically modulated space-charge potential. The distribution coefficients for Te and Zn in GaP were found, at 630 °C, to be 34 and 3.0×10−3, respectively.

OMVPE Growth of GalnAs/InP Quantum Well Structures

ABSTRACTInP/GalnAs/InP quantum well structures have been grown using atmospheric pressure organometallic vapor phase epitaxy (AP-OMVPE). The optimum conditions for growth of extremely abrupt interfaces were studied. The optimum orientation was exactly (100). The growth had to be interrupted for 40 seconds at the first interface and 2 minutes at the 2nd interface to obtain the most abrupt interfaces. The narrowest photoluminescence half widths were obtained at the lowest values (31) of V/III ratio in the input vapor phase. These growth conditions allow the growth of wells as thin as &lt;10Å with photoluminescence (PL) spectra consisting of doublets or triplets. The extremely narrow peaks correspond to regions of the quantum well differing in thickness by a single monolayer. The energy separations of the neighboring peaks are found to increase with decreasing well width until, at a thickness of approximately 12 Å, the separation begins to decrease rapidly with decreasing well width. The exciton binding energies in the quantum wells have also been measured using thermally modulated PL. The binding energy is found to increase with decreasing well width until a maximum value of approximately 17 meV is measured for a nominal well width of approximately 13 Å. For thinner wells the exciton binding energy is found to decrease with decreasing well width.

Growth of ultrapure InP by atmospheric pressure organometallic vapor phase epitaxy

We report the growth and characterization of ultrapure InP using trimethylindium and phosphine by atmospheric pressure organometallic vapor phase epitaxy (APOMVPE). The 77 K mobility of 131 000 cm2 /V s is the highest ever obtained by APOMVPE and among the highest ever measured for InP using any growth technique. The low-temperature photoluminescence measurements reveal that impurity reduction occurs at higher growth temperatures.

OMVPE growth of Ga xIn 1− xP/GaAs(Al yGa 1− yAs) heterostructures for optical and electronic device applications

Low pressure organometallic vapor phase epitaxy is used for the growth of Ga x In 1− x P lattice matched to GaAs and Al y Ga 1− y As buffer layers grown on GaAs substrates. Photoluminescence is used to determine lattice matched compositions. The group III gas phase composition required for lattice matching to Al 0.97Ga 0.03As is different than that for GaAs by 2–3%. Quantum well heterostructures of Al 0.97Ga 0.03As/Ga 0.5In 0.5P/Al 0.97Ga 0.03As as narrow as 30 Å exhibit photoluminescence. These materials are used to realize a GaAs/Al y Ga 1− y As graded index-separate confinement light emitting diode with a Ga 0.5In 0.5P active region. In addition, the GaAs/Ga 0.51In 0.49P interface shows electron accumulation suggesting a two-dimensional electron gas has formed at the interface. The growth, fabrication, and characterization of these device materials are discussed.

Doping studies for InP grown by organometallic vapor phase epitaxy

InP with doping levels as low as 8 × 10 13 cm -3 and 300 K mobilities as high as 5744 cm 2/V · s has been grown without intentional doping, using trimethylindium (TMIn) and phosphine in an atmospheric pressure organometallic vapor phase epitaxy (OMVPE) reactor. TMIn source purity was found to have a major effect on the carrier concentration and mobility of undoped InP. The dominant residual acceptor was identified as Zn. Using appropriate doping, both n- and p-type carrier concentrations of up to 10 19 cm -3 have been obtained in the present study. n-Type InP layers have been grown using diethyltelluride and silane as dopants. Te has a very high incorporation efficiency with k Te = 36. Si has a low and temperature dependent distribution coefficient, due to the slow pyrolysis of silane at the growth temperature. The maximum photoluminescence (PL) intensity for Te doped InP occurs at n = 2 × 10 17 cm -3. Si doped InP was found to have poor PL efficiency. Using dimethylzinc as a p-type dopant, a low distribution coefficient, k Zn = 2.8 × 10 -3, was found at 600°C, apparently due to the high vapor pressure of Zn. The PL intensity of Zn doped InP with p >; 10 18 cm -3 is comparable to that of similarly doped n-type samples.

GaInAs/InP quantum wells grown by organometallic vapor phase epitaxy

Single quantum well InP/Ga0.47In0.53As/InP structures have been fabricated using atmospheric pressure organometallic vapor phase epitaxy. The reactants were trimethylgallium, trimethylindium, arsine, and phosphine. The structures were characterized mainly using low-temperature (4 K) photoluminescence (PL). Three major changes in the PL emission were observed as the well thickness was decreased from 500 to 62 Å. The PL peak energy was observed to increase by 41 meV, slightly less than predicted from simple calculations. The PL intensity was found to increase, being proportional to the reciprocal well thickness. The PL intensity from the 62 Å well was found to be approximately 100× higher than for 1–2-μm-thick Ga0.47In0.53 As epitaxial layers. Finally, the half-width of the single PL peak was found to increase with decreasing well width. This was tentatively interpreted in terms of well size fluctuations due to an approximately 20 Å compositional transition at each interface.

Optimized growth of GRIN-SCH quantum well lasers by low pressure organometallic vapor phase epitaxy

Low pressure organometallic vapor phase epitaxy is used in fabrication of graded index-separate confinement heterostructure single quantum well lasers. Material properties of epitaxial GaAs and (AlGa)As are optimized by improved reactor design resulting in continuous growth of quantum wells (30 Å) and linearly graded heterostructures at growth rates of 530 Å/min. Computer control and data acquisition are used to monitor and adjust gas flow, valve switching and pressure during growth. Results on lasers with 150 Å wells emitting at 835 nm under pulsed conditions at room temperature given external power and slope efficiencies up to 27% and 67% respectively for 100 μ m stripes, with maximum output power exceeding 1.2 W/facet. External power and slope efficiencies for 5 μ m stripes are as high as 36% and 80% respectively with output powers up to 53 mW/facet. These are the best values yet reported for this type of structure grown by OMVPE. In this paper we present details of pertinent growth parameters required to realize these results.

Investigation of the properties of organometallic vapor phase epitaxially grown AlGaAs/GaAs heterostructures using Raman scattering

The growth of AlGaAs/GaAs heterostructures by low pressure organometallic vapor phase epitaxy was studied using Raman spectroscopy on a series of multilayer structures. Growth conditions were chosen to allow the investigation of the effects of growth rate and growth interruption during the formation of each type of interface (aluminum ‘‘turn on’’ and ‘‘turn off’’). This study represents the first report on the use of Raman for the quantitative measurement of the alloy composition in each region of a superlattice structure, where the observation is made that an extended growth interruption is required for the growth of thin GaAs regions (less than 100 Å) over AlGaAs (Al ‘‘turn off’’) while the other interface requires no growth interruption.