A. R. Clawson

MOVPE growth of SiO2-masked InP structures at reduced pressures

Abstract Selective area MOVPE growth of InP through windows in SiO 2 -masked (100) substrates has been investigated for the dependence of morphology on the reactor pressure. InP growth was from trimethylindium and phosphine at reactor pressures from 760 to 9 Torr. There is no deposition on the SiO 2 mask at reduced pressures; however, growth at the window edges is thicker than at the center. The edge growth decreases with reactor pressure so at 9 Torr the thickness across the windows is acceptably uniform. Flat-bottomed recesses have been etched through the windows using either 10% iodic acid or in-situ vapor etching with ethylene dibromide. InP growth to refill the recesses is uniform in thickness except at the window edges where it is limited by ridges of height equal to the layer thickness on the (111)B etch facet of 〈110〉 oriented edges and by void channels along the etch-undercut 〈110〉 oriented edges.

Study of Interrupted MOVPE Growth of lnGaAs/lnP Superlattice

Abstract The effects of growth interruption at the InGaAs/InP interface in metalorganic vapor phase epitaxial InGaAs/InP superlattice were examined with X-ray diffractometry and optical absorption spectroscopy. For superlattices grown with growth interruption in a phosphine ambient, both compressive strain and exciton absorption wavelength in the superlattice decrease with the interruption time. For superlattices grown with growth interruption in a hydrogen ambient, no significant change in compressive strain is observed. These results, combined with observations from a computer simulation of the X-ray rocking curve, indicate that, for our experimental configuration, the compositional graded InGaAs/InP interface extends widely into the subsequent InP and cannot be eliminated by short time growth interruption.

InP-on-InGaAs interface with Ga and In coverage in metalorganic vapor phase epitaxy of InGaAsInP superlattices

Abstract At the InP-on-InGaAs interface grown by metalorganic vapor phase epitaxy (MOVPE), reducing the As memory effect (As carryover) and simultaneously protecting the InGaAs surface against As-P exchange present a challenging problem in achieving a compositional abrupt and high quality interface. In this work, combinations of group III metalorganic sources were introduced at the InP-on-InGaAs interface in the absence of any hydrides. The results prove that severe As carryover exists at this interface. Furthermore, better interface quality is obtained when the InGaAs surface is covered with In rather than with Ga.

Interface strain in organometallic vapor phase epitaxy grown InGaAs/InP superlattices

The spatial distribution of strain in organometallic vapor phase epitaxy grown InGaAs/InP superlattice structures has been studied by varying the thicknesses of the InGaAs well and the InP barrier layers and measuring the strain. High resolution x-ray diffraction rocking curves were used to measure the strain from angular separation between the zeroth-order superlattice peak and the substrate (004) peak. The results are consistent with a compressive strain resulting from arsenic carryover into the InP following InGaAs growth. The strain is not localized at the interfaces but extends into the InP barrier layer. The amount of arsenic carryover increases with the growth time of the InGaAs well.

Interface strain in InGaAs-InP superlattices

Strain has been measured within (001) oriented OMVPE grown multilayer superlattices consisting of thin As-compound layers in InP and thin P-compound layers in GaAs. From the strain behavior, it is interpreted that As rapidly replaces P on an InP surface exposed to AsH3 and P slowly replaces As on a As-terminated surface exposed to PH3. This results in incorporation of an InAs-like strain in InP whose magnitude depends on the nature of the As-terminated surface. At growth temperatures above 600°C, the strain is equivalent to about one monolayer of InAs; while below 600°C, it is equivalent to two monolayers of InAs. PH3 interaction with GaAs surfaces is sufficiently slow that GaP-like strain is observed only when deliberate interrupts under PH3 are introduced. GaP grown on GaAs at 650°C is found to incorporate enough residual As to sustain a layer composition of GaAs0.5P0.5 over the first several monolayers.

Effects of the gas ambient in thermal activation of Mg-doped p-GaN on Hall effect and photoluminescence

The effects of thermal annealing in N2, O2, Ar or mixed gas ambient on the electrical and optical properties of metal-organic-chemical-vapor-deposition-grown Mg-doped p-type GaN were investigated by Hall effect and photoluminescence. A systematical study on optimizing annealing gas combination, time, and temperature for achieving high activation efficiency of Mg acceptors was conducted simultaneously. High hole concentration of 9.07 × 1017 cm−3 and low resistivity of 0.622 Ω-cm using the optimized annealing condition were achieved. In agreement with some previous studies, annealing in the mixed gas ambient of N2 and O2 provided significant improvements in activation efficiency of Mg acceptors compared with annealing in pure O2, N2, or Ar. The room- and low-temperature photoluminescence spectra measured from the samples annealed in N2-rich ambient showed significantly higher photoluminescence intensity at both 2.8- and 3.2-eV band transitions. Consistent with the study of others, the experimental results o...

Waveguide photodiodes for high-speed detection

This paper reviews the waveguide photodiode development for high power and high speed operation.

Strain from modified interface compositions in InGaAs/InP superlattices

Thin strained regions have been inserted at the interfaces of lattice-matched InGaAs/lnP superlattices to assess growth conditions for tailoring of localized compositional changes and for studying As-P intermixing behavior during heterojunction growth. Also, precise growth rates of binary composition layers were determined from specially designed superlattices using strained layers of common anion compounds inserted periodically into InP and GaAs. Growth rates of fractional monolayers are found to be identical to thick layer growth rates. When thin InAs, GaAs, GaP, ALAs, or AIP layers were inserted at the InGaAs/lnP heterojunctions, the measured strain at either one or both interfaces was equal to the strain predicted from the growth rate x time product. Excess strain seen in some cases is due to a change in As-P intermixing and this component can be separated from the predicted strain. Insertion of Ga-compounds at the InP-grown-on-InGaAs interface causes interface roughening which degrades the superlattice. For all other compositions the thin, highly strained regions are not detrimental to the crystalline quality of the periodic structure.

Strained-layer InAsP/InGaP MQWs grown by MOVPE

Strained balanced InAsP/InGaP superlattices for optoelectronic applications were studied with materials grown by low pressure MOVPE. For 20 and 30 period InAsP/InGaP superlattices with a 23 percent As mole fraction in the InAsP layers, sharp x-ray satellite peaks are obtained. The superlattices show an average lattice constant close to that of the InP substrate. Strong photoluminescence with narrow emission linewidth are observed at room temperature around 1.11 micrometers . PIN diodes with an intrinsic region consisting of the InAsP/InGaP superlattice show efficient electroabsorption at wavelengths around 1.15 micrometers with a small residual absorption of 59 cm-1.