David W. Kisker

GaInAsSb metastable alloys grown by organometallic vapor phase epitaxy

Ga1−xInxAs1−ySby alloys have been grown by organometallic vapor phase epitaxy using trimethyl compounds of Ga, In, As, and Sb(TMGa, TMIn, TMAs, and TMSb) plus AsH3 in an atmospheric pressure, horizontal, infrared heated reactor. For the first time, alloys near the center of the region of solid immiscibility have been grown. Alloys with room‐temperature band gaps of 0.45 eV (Ga0.68In0.32As0.28Sb0.72) and 0.37 eV (Ga0.26In0.74As0.76Sb0.24) have been grown on GaSb substrates and alloys with larger band gaps (0.74 eV for Ga0.71In0.29As0.76Sb0.24) have been grown on InP substrates. The smaller band‐gap alloys are grown at temperatures as low as 486 °C. The alloys on InP substrates are grown at higher temperatures of 600 °C, more typical of the GaAsSb and GaInAs alloys reported earlier. Solid composition was determined using energy dispersive x‐ray analysis and combined x‐ray diffraction and photoluminescence measurements. The low‐temperature photoluminescence of these metastable alloys consists of a single, pr...

Influence of Ga‐As‐Te interfacial phases on the orientation of epitaxial CdTe on GaAs

When CdTe is grown by molecular beam or organometallic vapor phase epitaxy on (100) GaAs, the layer can grow with either a (100) or (111) orientation. Reflection high‐energy electron diffraction and Auger studies are presented here which show that adsorption of different submonolayer amounts of Te on a GaAs surface can change the surface symmetry and the resulting CdTe orientation. A precursor surface to (111) growth results from the formation of a relatively Te‐poor Ga‐As‐Te surface phase. A relatively Te‐rich structure yields a surface with (100) symmetry and lead to (100) growth.

Efficient generation of 480 fs electrical pulses on transmission lines by photoconductive switching in metalorganic chemical vapor deposited CdTe

We have generated electrical pulses of only 480 fs duration by photoconductive switching in CdTe grown by ultraviolet‐enhanced metalorganic chemical vapor deposition (MOCVD). In addition to the extremely fast switching times, MOCVD CdTe also exhibits a high mobility of 180 cm2/V s and can be grown on almost any substrate, making it ideal for integration into existing circuits and devices.

Propagation of picosecond electrical pulses on a silicon‐based microstrip line with buried cobalt silicide ground plane

A microstrip line with a highly conducting cobalt silicide (CoSi2) ground plane buried 7 μm below the surface of a single‐crystal silicon wafer is presented. This new transmission line shows significantly reduced dispersion up to 100 GHz bandwidth compared to a conventional microstrip line with the ground plane on the back of the substrate, while being able to support active devices in the silicon dielectric. After propagating 5 mm, the rise time (10%–90%) of an electrical pulse increases only from 2.5 to 3.7 ps as opposed to an increase from 2.7 to 11.3 ps on a conventional microstrip line.

Molecular beam epitaxial growth of In1−xGaxAs1−ySby lattice matched to GaSb

We have succeeded in growing epitaxial layers and multilayer heterostructures of In1−xGaxAs1−ySby quaternary and InAs0.92Sb0.08 ternary alloys lattice matched to GaSb by molecular beam epitaxy. High quality epilayers with lattice mismatch Δa/a∼8×10−4, excellent morphology, and efficient photoluminescence were grown. The surface reconstructions during growth of these quaternary and ternary alloys were also investigated using in situ reflection high‐energy electron diffraction.We have succeeded in growing epitaxial layers and multilayer heterostructures of In1−xGaxAs1−ySby quaternary and InAs0.92Sb0.08 ternary alloys lattice matched to GaSb by molecular beam epitaxy. High quality epilayers with lattice mismatch Δa/a∼8×10−4, excellent morphology, and efficient photoluminescence were grown. The surface reconstructions during growth of these quaternary and ternary alloys were also investigated using in situ reflection high‐energy electron diffraction.

Experimental considerations for in situ X-ray scattering analysis of OMVPE growth

Abstract We have recently performed a set of experiments using a chamber for growth of semiconductor single crystal films via organometallic vapor phase epitaxy (OMVPE) while simultaneously scattering X-rays from the growing crystal surface. Due to the special complications of OMVPE growth, such as near-atmospheric pressures, toxic and flammable gases, and high substrate temperatures, the chamber design includes many novel features. In this paper we will discuss the advantages of the z -axis diffractometer for such a chamber and the specific solutions to problems such as convective flow near the sample and film growth on the Be windows attached to the growth chamber. The X-rays enter the chamber through a 35-mm-diameter Be window mounted on a 2.75 in. UHV flange; they exit through a separate window which allows detection of X-rays from −5° to 125° in 2θ and take-off angles from the surface from −5° to 45°. Results from our experimental run on the PEP storage ring studying the growth of ZnSe on GaAs will be discussed.

X‐ray analysis of GaAs surface reconstructions in H2 and N2 atmospheres

In this work, we demonstrate the first in situ study of GaAs using grazing incidence x‐ray scattering during processing at 100 Torr prior to epitaxial film growth. Our results indicate that the native oxide is removed and a well‐ordered surface reconstruction is established at temperatures as low as 500 °C in hydrogen. In contrast, no surface reconstruction is observed when the substrate is heated in nitrogen at temperatures as high as 585 °C while comparable heating in hydrogen causes surface degradation in the form of liquid Ga droplets. These results suggest that a chemically induced surface transformation occurs rather than oxide evaporation during thermal treatment.

Low‐temperature organometallic vapor phase epitaxial growth of CdTe using a new organotellurium source

The growth of CdTe by organometallic vapor phase epitaxy has been accomplished at 250 °C, using a new tellurium source, dimethylditelluride. The compound decomposes at a much lower temperature than the corresponding monotelluride, apparently by reacting with a cadmium‐containing species to eliminate one tellurium atom. As a result, the temperature necessary for deposition of CdTe has been lowered from the range of 400 °C, thus making completely thermally driven chemical vapor deposition of II‐VI compounds possible at much lower temperatures.

High quality long‐wavelength lasers grown by atmospheric organometallic vapor phase epitaxy using tertiarybutylarsine

High quality long‐wavelength InGaAsP/InP lasers were grown by atmospheric organometallic vapor phase epitaxy using tertiarybutylarsine (TBA) as a substitute for AsH3. Electrical and photoluminescence measurements on InGaAs and InGaAsP showed that TBA‐grown material was at least as good as AsH3 material in terms of suitability for lasers. From two wafers grown by TBA, current thresholds Ith as low as 11 mA were obtained for a 2‐μm‐wide semi‐insulating blocking planar buried heterostructure laser lasing near 1.3 μm wavelength. The differential quantum efficiencies ηD were as high as 21%/facet with a low internal loss α=21 cm−1. In addition Ith as low as 18 mA and ηD as high as 18% have been obtained for multiplequantum well lasers at 1.54 μm wavelength. These results show that TBA might be used to replace AsH3 without compromising on laser performance.

In situ characterization of organometallic growth of ZnSe using grazing incidence X-ray scattering

Abstract We have used in situ grazing incidence x-ray scattering to probe the near atmospheric pressure (100 Torr) OMVPE growth of ZnSe on GaAs. For the first time, we have directly observed the establishment of a clean GaAs surface in a hydrogen ambient with a characteristic (2×4) reconstruction and followed the development of the ZnSe epitaxial film during the initial stages of growth. Our results indicate the presence of a very stable and well-ordered p(2×1) reconstruction during growth, despite the presence of the ambient carrier gas and organic reaction by-products. In addition, by observing the changes in X-ray reflectivity due to the introduction of source compounds, we have also been able to investigate kinetic effects during alternating source growth.