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Oxide films of the quality required for the fabrication of electronic and photonic devices are typically deposited at elevated temperatures and thermal equilibrium, thereby adversely impacting thermal budgets. We report the deposition and patterning of silicon dioxide (SiO2) films of high electrical and optical quality on Si(100) or polymer substrates in a N2 atmosphere and at 300 K by the photochemical conversion of thin liquid tetraethoxysilane (TEOS) layers with narrowband vacuum ultraviolet radiation [vacuum ultraviolet (VUV), 172 nm] provided by efficient microplasma lamps. Irradiating liquid TEOS layers, produced by spin-coating the precursor onto a substrate, with a VUV intensity of 13 mW cm−2, yields 40 nm-thick SiO2 films having a dielectric breakdown strength (Eb) of 5 MV cm−1, for which no precedent exists in the deposition of oxide films at 300 K. If room temperature-deposited films are post-annealed at 200 °C, Eb rises to 7.5 MV cm−1, which is <12% below the measured value (8.5 MV cm−1) for 40 nm SiO2 films grown by thermal oxidation. The deposition of 1 µm thick, stoichiometric SiO2 films requires only 20 min of VUV illumination at low optical fluences, and films with thicknesses of ∼35–60 nm exhibit a refractive index of 1.45 (633 nm). X-ray photoelectron spectrometry and Rutherford backscattering analysis indicate that, despite the deposition temperature, hydrocarbon impurity levels are near or below the detection limit. The capability for depositing 960 nm-thick SiO2 films uniformly (to within 0.6%) by liquid → solid photochemical conversion over a 5 cm diameter Si substrate and patterning films onto flexible polymer substrates has also been demonstrated. [ABSTRACT FROM AUTHOR]

Adaptation of wet chemical processing or replica molding techniques to microcavity plasma device technology has yielded lightweight and flexible arrays in the Al/[Al.sub.2][O.sub.3] materials system and plastic substrates, respectively. Microplasma arrays fabricated from two bonded sections of Al mesh with an integral dielectric barrier of nanoporous alumina have an overall thickness of < 100 [micro]m, resulting in lamps that are flexible and conformable to a variety of surfaces. Operating these arrays in both flat and curved configurations reveals few changes to the voltage-current characteristics but a reduction of a factor of two in the luminance of curved or bent structures relative to that for a flat array. Truncated paraboloid cavities have also been formed in 30-70-[micro]m-thick Al foil by a sequence of wet chemical processes. Microcavities with an emitting aperture diameter as small as 50 [micro]m have been realized, and arrays comprising [10.sup.4] cavities exhibit ignition voltages of ~140-150 V (rms) for Ne pressures between 400 and 700 torr and a 20-kHz sinusoidal voltage waveform. Mixtures of Ne and Xe with Xe content up to 67% have been operated successfully. Ignition voltages of only 70-90 V (rms) have been measured for 30 x 30 arrays of 200 x 200-[micro][m.sup.2] microcavities formed in ultraviolet curable polymer by replica molding and operating in 400-600 torr of Ne. For 3% [N.sub.2]/Ar mixtures at total pressures of 400-700 torr, the ignition voltages rise to ~150-220 [V.sub.RMS] for a driving frequency of 20 kHz, the array emission is spatially uniform, and rms currents above 85 mA can be drawn in the steady state by these plastic-based arrays. Index Terms--Atmospheric plasmas, microplasma arrays, microplasmas.

A little more than two decades after the introduction of the first microcavity plasma devices, a growing body of commercial products based on the remarkable properties of these low‐temperature, atmospheric plasmas is now available. Following a brief review of early microplasma lamp development, this article describes microplasma‐based devices and systems currently being manufactured for applications in photolithography, photopatterning, and other nanofabrication processes, such as atomic layer deposition, spectroscopic identification and analysis of materials (including wide bandgap crystals), the disinfection of drinking water in off‐grid communities, deactivating COVID‐19 and other pathogens in air and on surfaces in public spaces, and vacuum ultraviolet lamps for driving atomic clocks. The microplasma‐based treatment of otitis media in the human ear will also be discussed. [ABSTRACT FROM AUTHOR]

The fabrication of lightweight and optically transparent arrays of microplasma devices having microcavities fabricated by a polymer-based replica molding process is reported. This process enables arrays of microcavity plasma devices and connecting channels with feature sizes as small as 20 J. [micro]m to be produced inexpensively and precisely over surface areas of at least tens of square centimeters. Devices having transparent electrodes and substrates (including glass and flexible plastic) have been operated successfully at rare gas pressures up to 700 torr. Individual microplasma pixels with cross-sectional dimensions of 200 x 200 [micro][m.sup.2] and 50 x 50 [micro][m.sup.2], as well as plasma channels having widths of 20 and 150 [micro]m and aspect ratios (channel length : width) as large as [10.sup.4]:1, have been fabricated and tested. Representative voltage-current data for these structures and lifetime measurements for a 20 x 20 pixel array are presented. [2006-0099] Index Terms--Flexible display, microcavity plasmas, replication process, transparent display.

A two-dimensional fluid simulation of microplasmas is used to study the ac-driven cylindrical microactivity plasma devices. The analysis reveals that an annular discharge can be easily produced by increasing the gas pressure, which in turn leads to a negative glow in the vicinity of the microcavity wall.

In this paper, we report the development of hollow-cathode micro plasma devices made using micromachining techniques. Compared with larger discharge devices, micromachined discharge devices operate at much higher pressures, up to 1 atm. Linear current-voltage relationships are obtained, potentially simplifying the control electronics for such devices. The size of micromachined discharge units is reduced and the distribution of sizes and light intensity in an array is more uniform relative to previous devices. [721] Index Terms--Hollow cathode, microdischarge, micromachine.

The output power of the green lambda nearly equal to 549 nm holonium-doped fluorozirconate glass (ZBLAN) fiber laser, is a function of the absorbed pump power and fiber length. The output power, temporal and tuning characteristics of the green ZBLAN are studied with fiber laser pumped in the red, with lambda nearly equal to 643 nm. The slope efficiency and wide tunability of this fiber laser are suitable for applications that need green radiation.

A longstanding barrier to laser imaging with high spatial and temporal resolution is speckle, the granular interference pattern arising from the coherent interaction of laser radiation with the topography of an illuminated surface. Over the past five decades, scores of mechanical and optical approaches to mitigating or eliminating the impact of speckle have been proposed, including dynamic diffusers, degenerate optical cavities, and random lasers. We describe a laser resonator architecture that allows the spatial coherence and the associated speckle contrast ratio (C) of the laser output to be varied continuously while providing the power necessary for optical imaging of dynamic objects and phenomena with sub-10 ns resolution. Stabilization of a Fabry–Pérot optical cavity with an internal array of microlenses generates thousands of mutually incoherent, parallel microlaser beams, which merge in the far field to form a single beam having a near-Gaussian transverse intensity distribution. For this laser illuminator, C scales as 1 / N , where N is the number of microlasers in the array. When Ti:Al2O3 serves as the gain medium, composite beams comprising N > 1000 microbeams are generated with a divergence angle of ∼5 mrad and C < 0.03 for single pulse energies of 8 mJ (∼1 MW peak power). To illustrate the capability of this tunable spatial-coherence laser, images of Drosophila melanogaster in flight and turbomolecular pump vanes rotating at 56 000 rpm are presented. Owing to the brightness and pulse energies available with this laser, imaging a target at a distance of 5 m through dense fog with ∼250 μm resolution has been demonstrated. [ABSTRACT FROM AUTHOR]

Cellulose is a glucose polymer and the most abundant biological material on earth. Because it is biodegradable and yet water insoluble, cellulose has been pursued in the past as a scaffold or base structural material for medical applications, sensors, and optical devices. Patterning of two cellulose polymers, cellulose acetate and cellulose acetate butyrate, by photoablative lithography at 172 nm has been demonstrated and is reported here. This 3D subtractive process yields complex micro- and nanostructures and optical components, including sinusoidal gratings and waveguides. Having a depth precision of 15 nm and requiring no photoresist or solvents, vacuum-ultraviolet photoetching of cellulose polymer films proceeds at a constant rate of ∼0.8 μm/h for depths of up to and beyond 25 μm when the intensity of the flat lamp is 10 mW cm−2. A polydimethylsiloxane (PDMS) microimprinting process, in which photoetched cellulose serves as a negative master mold for PDMS, provides feature sizes as small as 0.5 μm and allows for optical structures such as gratings to be integrated with microfluidic devices while eliminating the existing necessity of fabricating Si molds in a cleanroom environment. [ABSTRACT FROM AUTHOR]

Two color optical pumping, both above (anti-Stokes pump or ASP) and below (Stokes pump) the lasing wavelength, was adopted to reduce the net quantum defect (QD) in a solid-state Yb-doped fiber laser. The reduction in QD was achieved by converting a substantial portion of the gain medium's phonons directly into useful photons through a dual-wavelength excitation (DWE) mechanism. Since this is achieved through the usual processes of absorption and stimulated emission associated with lasing, high efficiency can be maintained. Both time domain and power measurements are presented, demonstrating a 13.2% reduction of the system's net QD and a 13.8% reduction in the lasing threshold power. These values were limited only by the available ASP power. Laser slope efficiency, with respect to launched ASP power, was found to be as high as 38.3%. A finite difference time domain model, developed to elucidate the role of both pumps in populating the upper states, corroborated the experimental findings. The DWE concept proposed here opens the door to an "excitation-balanced" type of self-cooled fiber laser. Simulation results also suggest that the technique is scalable and conceptually applicable to other solid-state laser systems. [ABSTRACT FROM AUTHOR]

Mercury trapped ion clocks have demonstrated great long-term frequency stability and robustness. In this paper, we report a demonstration of an integrated 100-cc physics package in an effort to develop a micromercury trapped ion clock with high frequency stability. The physics package consists of a sealed 30-cc vacuum tube with one layer of magnetic shielding, light source, and detector assembly. A field emitter array and a 194-nm microplasma lamp were employed together with a microtrap tube to reduce the size and power consumption for a mercury trapped ion clock. We show that the 100-cc physics package is capable of providing a fractional frequency stability of 1 × 10 − 11 τ − 1 / 2 down to 5 × 10 − 14 after a few hours of integration. We also show a set of environmental sensitivity evaluations as well as the clock frequency retrace. [ABSTRACT FROM AUTHOR]

Aluminum oxide (Al2O3) films 15–185 nm in thickness have been grown on Si(100) by a modified atomic layer deposition (ALD) process in which the oxygen precursor is dissociated by a 50 × 20 array of microcavity plasmas. The unique characteristics of microplasmas with respect to electron temperature, specific power loading, and operation at elevated pressures enable the efficient dissociation and excitation of strongly bound precursors such as O2. Microplasma arrays are also sufficiently compact so as to be situated in proximity to the substrate, thereby allowing for transient, excited atomic or molecular species to interact with the surface but without the attendant damage to the growing film or substrate inherent with direct plasma ALD systems. Conformal growth of the oxide within tapered Si trenches having depths up to 3.5 μm and widths below 40 nm is realized, and the mean variation in the thickness of 25 nm thick films is ∼0.3 nm over a 50 mm diameter Si wafer. For a substrate temperature (Ts) of 50 °C, the film growth rate remains constant at 2.25 Å/cycle up to ∼700 cycles, and surface analysis confirms the the O:Al stoichiometric ratio to be 1.52 ± 0.10. MOS capacitors fabricated from 30 nm thick Al2O3 films yield capacitance–voltage (C–V) curves at 1 MHz having a hysteresis of 100 mV that falls to <1 mV if the Al2O3 film is postannealed at 400 °C. The measured breakdown electric field strength for 30 nm films is 4.1 MV/cm for Ts = 50 °C (6.1 MV/cm for postannealed films). Patterned, 68 nm thick films with lateral dimensions <2 μm have also been realized by film growth at 50 °C and the subsequent lift-off of a photoresist. By patterning features with e-beam lithography prior to film growth and lift-off, we have fabricated arrays of ∼210 nm diameter Al2O3 discs (and diamonds). [ABSTRACT FROM AUTHOR]

Cylindrical microcavity plasma devices with diameters (D) in the 100–300 μm range and a dielectric barrier structure similar to that described by Park et al. [J. Appl. Phys. 99, 026107 (2006)] for Al/Al2O3 devices have been investigated numerically. A two-dimensional fluid simulation of microplasmas in Ne/7% Xe gas mixtures with pD values (where p is the total gas pressure) in the 3–9 Torr cm interval yields the temporal history of the spatially resolved electron and ion number densities in response to a 250 kHz bipolar excitation wave form. Calculations show two distinct regions of plasma development, along the microcavity axis and near the wall, each of which dominates the plasma characteristics in separate pD regions. For low pD values (<4 Torr cm), the negative glow produced at the cavity wall extends to the microcavity axis which, in combination with the strong axial electric field, produces an intense glow discharge on axis. For 4<=pD<=6 Torr cm, a weakened axial discharge is observed early in the life of the plasma but the radial variation of the electron density flattens. Further increases in the gas pressure (to the largest pD values investigated, 6–9 Torr cm) result in the retreat of the negative glow to the vicinity of the microcavity wall, thereby producing a diffuse but annular discharge. Even at the higher pD values, the axial discharge appears to facilitate ignition of the negative glow. The predictions of the simulations are consistent with the behavior of Al/Al2O3 microplasma devices for which D=100–300 μm. [ABSTRACT FROM AUTHOR]

Self-organization of periodic, streamer-like ionization waves in planar microplasma devices having a dielectric barrier discharge structure is observed. In contrast to plasma propagation in arrays of microchannels or microcavities, the ionization waves originate from a single point but rapidly sub-divide into as many as 10 'branch' plasma wave packets that eventually recombine. In less than 70 ns, the self-organization of the spatially-periodic array of co-propagating branches is complete and two successive sets of waves, separated in distance and time by ∼1.8 mm and ∼50 ns, respectively, are generated. The mean propagation velocity of each plasma packet is greater than 70 km s−1 but values as large as 150 km s−1 have been measured. Because the propagation path for all subsequent streamers is established by the first set of plasma packets, the intensity of the second set is noticeably enhanced. The average length of the primary branches is ∼1.5 mm but reaches a maximum of ∼4.5 mm as the wave packets travel an overall distance of 1 cm. These phenomena are interpreted in terms of photoelectron emission from the floor and walls of the shallow dielectric microcavity, induced by radiation from the advancing packets, and the rapid collapse of the sheath of each microplasma owing to the accumulation of charge on the underlying dielectric. The spatial profiles of the propagating plasmas suggest that generating and probing plasma solitons may now be feasible. [ABSTRACT FROM AUTHOR]

Fractals are ubiquitous in nature, and prominent examples include snowflakes and neurons. Although it has long been known that intricate optical fractal patterns can be realized with components such as gratings and reflecting spheres, generating fractal transverse modes from a laser has proven to be elusive. By introducing a 2D network of microspheres into a Fabry-Pérot cavity bounding a gain medium, we demonstrate a hybrid optical resonator in which the spheres enable the simultaneous generation of arrays of conventional (Gaussian) and fractal laser modes. Within the interstices of the microsphere crystal, several distinct fractal modes are observed, two of which resemble the Sierpinski Triangle. Coupling between adjacent fractal modes is evident, and fractal modes may be synthesized through design of the microsphere network. Owing to a unique synergy between the gain medium and the resonator, this optical platform is able to emit hundreds of microlaser beams and probe live motile cells. [ABSTRACT FROM AUTHOR]

Microchemical reactors consisting of parallel linear arrays of interconnected cylindrical microcavity plasma devices have been fabricated by replica molding in ultraviolet-curable polymer. Tests of 10 x 10 arrays of 400-[micro]m-diameter devices with 125-[micro]m-wide gas flow channels have been conducted in rare gas and Ar/C[S.sub.2] flows and excitation of the array with a sinusoidal voltage. Visible chemiluminescence ([lambda] ~ 505 nm) resulting from the [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] transition of C[S.sup.+.sub.2] and the deposition of a [(C-S).sub.n] microstructured polymer have been observed in the Ar/C[S.sub.2] flow experiments. Index Terms--Chemiluminescence, microchannels, microchemical reactor, microplasmas.

Low-temperature nonequilibrium plasma has been produced within the microcavities of a single sheet of aluminum wire fabric. The fabric is composed of two sets of interwoven, orthogonally oriented Al wires and each of the sets serves as an electrode for the array of dielectric barrier devices. Carefully controlled anodization of the fabric electrically and chemically isolates the two sets of wires from each other with a thin barrier of nanoporous aluminum oxide. The resulting material is flexible, and cylindrical microcavity plasma lamps operating in Ne have been demonstrated. Index Terms--Microcavities, microplasmas, plasma sheets, wire fabric.

Microplasma arrays and channels fabricated on plastic substrates by replica molding are well suited for biomolecule detection in liquid flow streams. Arrays of orthogonally oriented linear channels with cross-sectional areas of 100 x 100 [micro][m.sup.2] have been operated in Ar/3% [N.sub.2] gas mixtures at atmospheric pressure. Similar experiments with arrays of parallel linear channels having cross-sectional areas of 200 x 100 [micro][m.sup.2] and lengths of 6 cm have also been conducted. Spatially uniform emission in the near ultraviolet ([lambda] ~300-400 nm) from the microcavity plasma sources and the photoluminescence of organic molecules in solution in adjoining channels have been observed. Index Terms--Biophotonics, microchannels, microplasmas, ultraviolet.

Time-resolved imaging of an array of silicon based micro-cavity discharge devices, operating in helium at 700 Torr, is presented. The array is shown to ignite four times per cycle, with the brightest emission corresponding to a distinct current peak in the negative phase of the applied sinusoidal voltage. The cavities do not ignite simultaneously and the instantaneous intensity across the array is non-uniform. Before the brightest emission peak is reached, optical imaging shows some of the cavities to be ignited. During the emission peak, neighboring cavities are successively ignited, resulting in two emission regions which propagate across the array with wavefront velocities of 3 and 6 km/s. Index Terms--Atmospheric pressure glow discharge, helium, micro-discharge, optical imaging.

Images of the Ne plasma plume residing above the microcavity of a Si inverted square pyramid microdischarge device have been obtained with an uptical telescope and a charged-coupled device camera. Viewing the discharge along the device surface show the plume to be approximately hemispherical with a bright core having a width (at the surface) of ~140 [micro]m for [P.sub.Ne] = 300 torr. The dependence of the plume contour on pressure is in qualitative agreement with recent computational results (Kushner, 2004). Index Terms--Fluorescence, microcavity plasma, microdischarge.

Atomic and molecular emissions provide a convenient diagnostic of the spatial uniformity of the electrical characteristics of Si microcavity discharge arrays. 10 x 10 arrays of [(50 [micro]m).sup.2], inverted pyramidal Si microcavity pixels have been studied with Ne, Ar, and Ar/[N.sub.2] gas mixtures at pressures up to 800 tort. Nonuniform power loading of pixels in the array, as well as the comparative strength of the electric field within each pixel at the device perimeter, are evident from images of the surface emission from the array. Index Terms--Arrays, atomic and molecular emission, microdischarges, plasmas.

Spatially uniform microdischarges in Xe at pressures of 300-800 torr have been produced in a 90-[micro]m gap between 1.5-mm-diameter tungsten rods (plasma volume of ~160 [micro]L), and applied to the laser spectroscopy of the [Xe.sub.2] excimer. Calculations and spectral simulations indicate that the gas temperature in the plasma reaches 900 K for a steady-state current density of 0.23 A-[cm.sup.-2]. Laser-induced, fluorescence suppression spectroscopy in the afterglow of the crow-barred discharge reveals well-developed vibrational bands in the 680-800-nm region tentatively attributed to 5([1.sub.g]) [left arrow] [a.sup.3] [[SIGMA].sup.+.sub.u] ([1.sub.u], [0.sup.-.sub.u]) transitions of [Xe.sub.2]. Index Terms--Laser spectroscopy, microdischarge, molecular spectroscopy.

Lasing in the 602-620 nm (orange-red) spectral region has been observed from R-phycoerythrin (RPE), a phycobiliprotein responsible for the >80% quantum yield of red algae. Photoexcitation of 8 μM RPE solutions in a Fabry-Pérot resonator with frequency-doubled Nd:YAG laser pulses (λp = 532 nm) yields >26 nJ of energy in ~2.5 ns (FWHM) pulses, which corresponds to >10 W of peak power. Maximum laser emission occurs at ~610 nm, the threshold pump energy fluence is measured to be 260 ± 15 μJ/mm², and more than 100 longitudinal laser modes are generated when the cavity free spectral range and mirror separation are Δλ = 0.18 nm and L = 777 ± 1 μm, respectively. In combination with the known versatility of the phycobiliproteins as fluorescent tags, the biomolecular RPE laser reported here suggests its applicability to clinical assays and in situ laser imaging. [ABSTRACT FROM AUTHOR]

Laser physicist Howard Thomas Powell was born in 1944 and grew up in Woodland, WA. He gained a BS in physics from Caltech in 1966 and subsequently studied at Cornell University. He joined the McDonnell Douglas Research Laboratories as a research physicist in 1971.

Research describing holmium doped fluorozirconate glass fibre lasers is presented. In particular experiments using ring dye and high power InGaAlP diode lasers are investigated.

A hybrid optoplasmonic amplifier, injection-seeded by an internally-generated Raman signal and operating in the visible (563-675 nm), is proposed and evidence for amplification is presented. Comprising a gain medium tethered to a whispering gallery mode (WGM) resonator with a protein, and a plasmonic surface, the optical system described here selectively amplifies a single (or a few) Raman line(s) produced within the WGM resonator and is well-suited for routing narrowband optical power on-a-chip. Over the past five decades, optical oscillators and amplifiers have typically been based on the buildup of the field from the spontaneous emission background. Doing so limits the temporal coherence of the output, lengthens the time required for the optical field intensity to reach saturation, and often is responsible for complex, multiline spectra. In addition to the spectral control afforded by injection-locking, the effective Q of the amplifier can be specified by the bandwidth of the injected Raman signal. This characteristic contrasts with previous WGM-based lasers and amplifiers for which the Q is determined solely by the WGM resonator. [ABSTRACT FROM AUTHOR]

The fabrication of lightweight and optically transparent arrays of microplasma devices having microcavities fabricated by a polymer-based replica molding process is reported. This process enables arrays of microcavity plasma devices and connecting channels with feature sizes as small as 20 μm to be produced inexpensively and precisely over surface areas of at least tens of square centimeters. Devices having transparent electrodes and substrates (including glass and flexible plastic) have been operated successfully at rare gas pressures up to 700 torr. Individual microplasma pixels with cross-sectional dimensions of 200 × 200 μm2 and 50 × 50 μm2, as well as plasma channels having widths of 20 and 150 μm and aspect ratios (channel length : width) as large as 104 : 1, have been fabricated and tested. Representative voltage-current data for these structures and lifetime measurements for a 20 × 20 pixel array are presented. [ABSTRACT FROM AUTHOR]

Electrical breakdown of cold (room temperature) metal-halide arc lamps typically occurs through the fill of a rare gas (at a pressure of tens of Torrs) and the vapour produced by the metal donor. Restarting a warm lamp is often made difficult by the high pressure of the metal and metal-halide vapours. To reliably start cold lamps with a minimum voltage and a minimum sputtering of the electrodes, and to restart warm lamps that have a high pressure of the metal and metal-halide vapours, auxiliary sources of ionization are often used. As a point of departure for the study of these processes, measurements of formative breakdown times were made in a cylindrical discharge tube resembling a compact polycrystalline alumina envelope metal-halide lamp. Breakdown times were measured for Ar/Xe gas mixtures at total pressures of 10–90 Torr and biases up to 2 kV applied to a 1.6 cm gap. The data provide a knowledge base for a companion computational investigation. We found that breakdown times generally decreased with small admixtures of Xe in Ar (5–15%) and increased with larger admixtures. We attribute these trends to the changing shape of the tail of the electron energy distribution. [ABSTRACT FROM AUTHOR]

This letter describes the fabrication and performance of microplasma devices and arrays by a replica molding process in which the substrate is a flexible and ultraviolet (UV) transparent glass/polymer hybrid structure. In particular, ultrathin flexible glass sheets were embedded into the device so as to minimize outgassing of undesirable gas species and reinforce flexible substrates from the fatigue. Extended lifetime of the polymeric devices has been observed up to 200 h, with full recovery after refilling with gas. The major component of the devices has a high UV transmittance, and is transparent up to about 220 nm. [ABSTRACT FROM AUTHOR]

Thin films of Ge-Si alloys were deposited by 193 nm photolysis of GeH[sub 4]/Si[sub 2]H[sub 6], gas mixtures using an ArF laser. For substrate temperatures below 350 °C, deposition occurred only with the laser present, while for temperatures above 400 °C, film growth was little influenced by laser photolysis and resembled conventional chemical vapor deposition (CVD). The Si/Ge ratio in the films was about three times the P[sub Si[sub 2]H[sub 6]]/P[sub GeH[sub 4]], ratio of reactant partia1 pressures for deposition in either the laser photolysis or the CVD regime. This result indicates that there is strong cross chemistry between silicon and germanium-bearing species in the gas phase. Film stoichiometry was measured by Auger analysis and Raman spectroscopy, with both methods leading to the same film composition. [ABSTRACT FROM AUTHOR]