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21 Jun 1993

Volume 62, Issue 25, pp. 3223-3379

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Second‐order nonlinear optical properties of an aromatic polyurea exhibiting optical transparency down to 300 nm

Hari Singh Nalwa, Toshiyuki Watanabe, Atsushi Kakuta, Akio Mukoh, and Seizo Miyata

Appl. Phys. Lett. 62, 3223 (1993); http://dx.doi.org/10.1063/1.109080 (3 pages) | Cited 3 times

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We report here a new high performance organic polymer comprised of urea moieties for optical second‐harmonic generation. The nonlinear d33 coefficient of aromatic polyurea consisting of nonlinear optical chromophores in the main chain, estimated by Maker fringe measurements was found to be approximately 15 times that of KDP crystals at 1.064 μm. The decay of second‐order optical nonlinearity of poled polyurea films at ambient conditions was negligible and temporal study showed persistent optical nonlinearity at least 1000 h after poling. Aromatic polyurea films exhibited optical transparency down to ∼300 nm in UV region and optical transmission was greater than 99% from 350–2500 nm like conventional inorganic nonlinear optical materials. Aromatic polyurea is the first example of an organic nonlinear optical material showing optical transparency at such low wavelengths. The nonlinear efficiency transparency trade‐off demonstrates aromatic polyurea to be a new promising organic material for nonlinear optics.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.70.Jk Polymers and organics
78.66.Qn Polymers; organic compounds

Dynamics of resonant optical waveguide semiconductor laser arrays

Sujatha Ramanujan and Herbert G. Winful

Appl. Phys. Lett. 62, 3226 (1993); http://dx.doi.org/10.1063/1.109081 (3 pages) | Cited 1 time

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A propagation model is presented for the dynamics of antiguided semiconductor laser arrays. The model takes into account diffraction, carrier diffusion, spatial hole burning, and carrier‐induced antiguiding. Numerical results reveal a variety of spatiotemporal behaviors ranging from stable, quiescent operation to periodic and erratic intensity oscillations.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Voltage‐tunable multiple quantum well photodetector vertically integrated with voltage‐tunable multiple quantum well filter

K. W. Goossen, J. E. Cunningham, M. B. Santos, and W. Y. Jan

Appl. Phys. Lett. 62, 3229 (1993); http://dx.doi.org/10.1063/1.109082 (3 pages) | Cited 11 times

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We present a n‐i[multiple quantum well (MQW)]‐p‐i(MQW)‐n device wherein the bottom MQW functions as a voltage‐tunable photodetector and the top MQW functions as a voltage‐tunable filter, allowing enhanced detectivity at the exciton wavelength compared to photon energies below or above the band gap. Thus this device more closely approximates a true single wavelength, voltage‐tunable photodetector. We achieve about 2–1 selectivity over a tuning range of 14 nm with 12 V operation.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
78.66.Fd III-V semiconductors

Experimental verification of a longitudinal beam‐envelope model for a space‐charge dominated parabolic bunch

D. X. Wang, J. G. Wang, D. Kehne, and M. Reiser

Appl. Phys. Lett. 62, 3232 (1993); http://dx.doi.org/10.1063/1.109083 (3 pages) | Cited 8 times

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The longitudinal drift expansion and compression of a space‐charge dominated electron beam with a parabolic line charge profile has been studied experimentally to verify the validity of the longitudinal envelope equation. The experimental configuration and measurement results are reported. Good agreement is found between theoretical predictions from the envelope calculations and experimental results.
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41.85.Ja Particle beam transport
41.85.Ew Particle beam profile, beam intensity
29.27.Bd Beam dynamics; collective effects and instabilities
29.27.Fh Beam characteristics

Observations of the frequency range of self‐mode locking and single longitudinal mode operation in CuBr lasers

Jihong Geng, Guiyan Zhang, Xiudong Song, and Fucheng Lin

Appl. Phys. Lett. 62, 3235 (1993); http://dx.doi.org/10.1063/1.109084 (3 pages) | Cited 1 time

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The lower and upper limits of the longitudinal mode spacing and self‐mode locking behavior in CuBr lasers are reported for the first time, by using different optical cavity configurations. A proposed interpretation is given qualitatively. In addition, the first observation of single longitudinal mode operation in CuBr lasers with a multimirror cavity is described.
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42.55.Lt Gas lasers including excimer and metal-vapor lasers
42.60.Fc Modulation, tuning, and mode locking
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Novel structure of organic electroluminescence cells with conjugated oligomers

Chishio Hosokawa, Hisahiro Higashi, and Tadashi Kusumoto

Appl. Phys. Lett. 62, 3238 (1993); http://dx.doi.org/10.1063/1.109085 (3 pages) | Cited 55 times

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Organic electroluminescence (EL) cells with a novel structure, ITO/semiconducting oligothiophene layer/oligophenylene layer/emitting layer/Mg:Ag, were studied. The oligothiophene layer enhanced hole injection and hole transport into the emitting layer (EML), while the oligophenylene layer achieved electron confinement in EML by electron blocking. In addition, we found that the oligophenylene layer inhibited energy transfer from EML to the oligothiophene layer and played an important role in increasing the luminous efficiency. For our fabricated EL cell with tris(8‐hydroxyquinoline)aluminum as an emitting molecule, we succeeded in obtaining bright emission over 2000 cd/m2 at a voltage of about 10 V.
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78.60.Fi Electroluminescence
78.66.Qn Polymers; organic compounds
85.60.Jb Light-emitting devices
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Femtosecond optical dynamics of C60 and M3C60

S. B. Fleischer, E. P. Ippen, G. Dresselhaus, M. S. Dresselhaus, A. M. Rao, P. Zhou, and P. C. Eklund

Appl. Phys. Lett. 62, 3241 (1993); http://dx.doi.org/10.1063/1.109086 (3 pages) | Cited 26 times

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The initial, ultrafast scattering of optically excited carriers in M3C60 for M=K, Rb is investigated by femtosecond pump–probe measurements. An initial fast response (τ≊0.2 ps) of similar magnitude for both Rb3C60 and K3C60 is observed, while τ for undoped C60 is more than an order of magnitude longer. These results are discussed in terms of the molecular character of C60 and the bandlike character of M3C60.
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78.47.-p Spectroscopy of solid state dynamics
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.80.Jc Other crystalline inorganic semiconductors

Light emission in thermally oxidized porous silicon: Evidence for oxide‐related luminescence

S. M. Prokes

Appl. Phys. Lett. 62, 3244 (1993); http://dx.doi.org/10.1063/1.109087 (3 pages) | Cited 139 times

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The luminescence behavior of thermally oxidized porous silicon has been examined at various temperatures and times. No blue shifting of the photoluminescence has been noted with extended oxidation time (3–120 min), in a range where a 30% oxide thickness increase has been reported. This result does not easily fit the quantum confinement model, since the luminescence does not appear to depend on particle sizes. An oxide related luminescence, which is broad, in the red, and stable at high temperatures will be discussed as a possible source of this light emission.
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78.55.Hx Other solid inorganic materials
81.65.-b Surface treatments
78.40.Ha Other nonmetallic inorganics

Measured and simulated electron energy distribution functions in a low‐pressure radio frequency discharge in argon

M. M. Turner, R. A. Doyle, and M. B. Hopkins

Appl. Phys. Lett. 62, 3247 (1993); http://dx.doi.org/10.1063/1.109088 (3 pages) | Cited 16 times

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We report a combined experimental and computational study of a low‐pressure radio frequency discharge in argon. We have determined the electron energy distribution function experimentally using a Langmuir probe system and by simulation using the particle in cell method. A close comparison of these data shows good agreement over pressures from 20 to 200 mTorr. This pressure range encompasses the putative transition from a stochastic to an ohmic electron heating mode [V. A. Godyak and R. B. Piejak, Phys. Rev. Lett. 65, 996 (1990)]. The simulation does show such a transition, and we agree with earlier estimates of the transition pressure.
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52.80.Pi High-frequency and RF discharges
52.65.-y Plasma simulation
52.70.Gw Radio-frequency and microwave measurements

Fabrication and characteristics of 8‐hydroxyquinoline aluminum/aromatic diamine organic multiple quantum well and its use for electroluminescent diode

Yutaka Ohmori, Akihiko Fujii, Masao Uchida, Chikayoshi Morishima, and Katsumi Yoshino

Appl. Phys. Lett. 62, 3250 (1993); http://dx.doi.org/10.1063/1.109089 (3 pages) | Cited 52 times

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Multiple quantum well structure consisting of alternating layers of organic 8‐hydroxyquinoline aluminum (Alq3) and aromatic diamine (TPD) has been grown by organic molecular beam deposition. The multiple quantum well structure was determined by x‐ray diffraction, optical absorption, and photoluminescence. Photoluminescence peak of Alq3 shifts to higher energy with decreasing layer thickness, suggesting a quantum size effect. An electroluminescent diode has also been fabricated by using Alq3/TPD multiple quantum well structure.
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78.66.Qn Polymers; organic compounds
68.55.-a Thin film structure and morphology
78.55.Kz Solid organic materials
85.60.Jb Light-emitting devices

Sublimed C60 films for tribology

Bharat Bhushan, B. K. Gupta, Garrett W. Van Cleef, Cindy Capp, and James V. Coe

Appl. Phys. Lett. 62, 3253 (1993); http://dx.doi.org/10.1063/1.109090 (3 pages) | Cited 33 times

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Fullerenes take the form of hollow, geodesic domes, which are formed from a network of pentagons and hexagons. The C60 molecule has the highest possible symmetry (icosahedral) and assumes the shape of a soccer ball. At room temperature, fullerene molecules pack in a face‐centered‐cubic lattice bonded with weak van der Waals attractions. Fullerenes can be dissolved in solvents such as toluene and benzene and easily sublimed. The resilience, high load bearing capacity, low surface energy, high chemical stability, and spherical shape of C60 molecules and weak intermolecular bonding offer great potential for various mechanical and tribological applications. Sublimed films of C60 have been produced and friction and wear performance of these films in various operating environments are the subject of this letter.
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68.60.Bs Mechanical and acoustical properties
81.15.Jj Ion and electron beam-assisted deposition; ion plating
81.40.Pq Friction, lubrication, and wear

Noncontacting measurement of opaque thin films using a dual beam thermal wave probe

M. B. Suddendorf, M. Liu, and M. G. Somekh

Appl. Phys. Lett. 62, 3256 (1993); http://dx.doi.org/10.1063/1.109091 (3 pages) | Cited 3 times

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A dual beam thermal wave probe has been used to measure the thickness of opaque thin films in a noncontact, nondestructive manner. The method relies on the measurement of the differential phase of two interferometrically determined photodisplacement signals. The technique does not require calibration against standard samples and can be used to determine film thicknesses from a few tens of nanometers up to several micrometers. Alternatively, if the film thickness is known, thermal material properties like diffusivity or conductivity can be determined. The conditions under which the system is expected to give the most accurate results are analyzed.
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81.70.-q Methods of materials testing and analysis
07.60.Ly Interferometers
78.66.-w Optical properties of specific thin films
68.60.Dv Thermal stability; thermal effects

Study of Ge movement during thermal reactions between Pt and GeSi/Si heterostructures

Peixin Zhong and Youdou Zheng

Appl. Phys. Lett. 62, 3259 (1993); http://dx.doi.org/10.1063/1.109092 (3 pages) | Cited 8 times

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Germanium movement in the thermal reaction between Pt and the Ge0.15Si0.85/Si heterostructure was studied by Auger electron spectroscopy. The compounds formed were identified by x‐ray diffraction after various anneals from 300 to 760 °C. Pt2Ge and Pt2Si formed at low annealing temperatures. At higher temperatures, Pt(GexSi1−x) formed. Two types of Ge segregation were observed. Ge was rich at the surface and the PtGeSi/GeSi interface. Some Ge was pushed inward during thermal reaction at all of the above conditions. This procedure was enhanced by higher annealing temperature. Some Ge in the PtGeSi layer segregated to the surface. Both types of Ge segregation were strong after a 3 h, 300 °C anneal. The mechanism of the phenomena is discussed. This will have certain affects on the properties of PtGeSi/GeSi Schottky devices.
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68.35.Dv Composition, segregation; defects and impurities
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
73.30.+y Surface double layers, Schottky barriers, and work functions

Growth of stable dislocation‐free 3‐grain silicon ingots for thinner slicing

G. Martinelli and R. Kibizov

Appl. Phys. Lett. 62, 3262 (1993); http://dx.doi.org/10.1063/1.109093 (2 pages) | Cited 10 times

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Using the CZ technique we have set up a 3‐grain silicon ingot growing process which allows to obtain very large grains with a preselected orientation in order to facilitate thin slicing, a unanimously agreed upon requirement for photovoltaic applications. The 3‐grain ingots we obtained are particularly suitable for this aim since no cleavage plane {111} crosses the crystal obliquely to the slicing direction. Furthermore, this type of ingot allows a high growth rate ascribable to the verticality of its {111} side planes and has electrical and structure properties very close to those of single‐crystalline material.
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81.10.Aj Theory and models of crystal growth; physics and chemistry of crystal growth, crystal morphology, and orientation
81.10.Fq Growth from melts; zone melting and refining
84.60.Jt Photoelectric conversion

Reactive sputtering deposition of low temperature tantalum suboxide thin films

X. M. Wu, P. K. Wu, T.‐M. Lu, and E. J. Rymaszewski

Appl. Phys. Lett. 62, 3264 (1993); http://dx.doi.org/10.1063/1.109094 (3 pages) | Cited 25 times

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A relatively simple direct current sputtering deposition scheme has been employed to deposit 1000 Å tantalum oxide thin films at low temperature. At ≂190 °C substrate temperature, without further annealing, tantalum oxide films with a dielectric constant of 21–22 and a leakage current density as low as 10 nA/cm2 at 0.5 MV/cm electrical field strength (∼5 V of applied voltage) are obtained. These properties are achieved over a wide range of O2/Ar ratios when the total flow rate is kept constant. XPS measurements reveal that these films are nonstoichiometric with a composition of TaOx where x≂1.5. These low temperature, high dielectric constant thin films have potential applications as decoupling capacitors in very high speed electronic circuits and packaging.
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81.15.Cd Deposition by sputtering
77.55.-g Dielectric thin films
73.40.Rw Metal-insulator-metal structures

Microstructural transition and degraded opto‐electronic properties in amorphous SiGe:H alloys

S. J. Jones, Y. Chen, D. L. Williamson, R. Zedlitz, and G. Bauer

Appl. Phys. Lett. 62, 3267 (1993); http://dx.doi.org/10.1063/1.109095 (3 pages) | Cited 16 times

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The microstructure of amorphous Si1−xGex:H films with x<0.40 was studied using small‐angle x‐ray scattering (SAXS) and the results compared with those from opto‐electronic and density measurements. The SAXS, the sub‐band‐gap absorption determined from photothermal deflection spectroscopy, and the photo/dark conductivity ratio all show relatively sharp changes above x=0.2. A corresponding sharp change in the anisotropic character of the SAXS is consistent with a transition to a columnar‐like microstructure above x=0.2. The correlated results provide strong evidence for a direct link between degraded opto‐electronic properties and the increased heterogeneity associated with the microstructural transition.
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73.61.Jc Amorphous semiconductors; glasses
68.55.-a Thin film structure and morphology
73.50.Pz Photoconduction and photovoltaic effects

Intrinsic multiplexability of surface bistable nematic displays

R. Barberi, M. Giocondo, Ph. Martinot Lagarde, and G. Durand

Appl. Phys. Lett. 62, 3270 (1993); http://dx.doi.org/10.1063/1.109096 (3 pages) | Cited 2 times

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We present a simple multiplexing procedure for the flexoelectrically controlled surface bistable nematic display. When the surface anchoring is broken, the surface bifurcation between the two stable surface orientations has a very large sensitivity to external fields. This intrinsic property allows an easy multiplexing of the display. We excite each pixel with a sequence of two signals: a large driving square pulse of arbitrary polarity (or at high frequency), which breaks the surface anchoring, and a weak control square pulse, whose polarity determines the final texture of the pixel and hence its optical state. In a matrix geometry, the rows are sequentially addressed with the driving pulse. The columns are excited in parallel with the control pulse to write or erase the corresponding pixel.
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61.30.-v Liquid crystals
42.79.Kr Display devices, liquid-crystal devices

Comparison of Al electromigration in conventional Al alloy and W‐plug contacts to silicon

A. S. Oates, E. P. Martin, D. Alugbin, and F. Nkansah

Appl. Phys. Lett. 62, 3273 (1993); http://dx.doi.org/10.1063/1.109097 (3 pages) | Cited 10 times

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We examine the impact of the presence of a W plug on electromigration‐induced voiding of the Al alloy layer of contacts to silicon. By comparing conventional Al alloy and W‐plug contacts we show that the presence of the plug does not significantly improve the intrinsic susceptibility of contacts to Al voiding despite the elimination of the Al step coverage problem. Both the conventional Al alloy and W‐plug contacts degrade by drift of the Al layer with a velocity that is not influenced by the contact structure. The sheet resistance of the underlayer material of multilayer conductors plays an important role in influencing failure times since it determines the rate of resistance increase due to electromigration.
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66.30.Qa Electromigration
66.30.Fq Self-diffusion in metals, semimetals, and alloys
85.40.Ls Metallization, contacts, interconnects; device isolation
61.72.Qq Microscopic defects (voids, inclusions, etc.)

Atomic configuration dependent secondary electron emission from reconstructed silicon surfaces

Yoshikazu Homma, Mineharu Suzuki, and Masato Tomita

Appl. Phys. Lett. 62, 3276 (1993); http://dx.doi.org/10.1063/1.109098 (3 pages) | Cited 31 times

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We show that domains of reconstructed silicon surfaces can be imaged by secondary electrons (SEs) using an ultrahigh vacuum scanning electron microscope with a SE detector having angular resolvability. The SE images clearly show the double domain structure, alternate 2×1 and 1×2 domains on Si(100), as well as the coexistence of the reconstructed 7×7 domains and the nonreconstructed 1×1 domains on Si(111). These results demonstrate that SE emission is sensitive to the atomic configuration of the topmost layers. We call this scanning electron microscopy based technique for top layer imaging as scanning electron surface microscopy, which will evolve into a useful tool for surface characterization.
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68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)
79.20.Hx Electron impact: secondary emission
68.35.B- Structure of clean surfaces (and surface reconstruction)

Time dependence of the surface Fermi level of GaAs in atmosphere

I. Ohbu, M. Takahama, and H. Mizuta

Appl. Phys. Lett. 62, 3279 (1993); http://dx.doi.org/10.1063/1.109099 (3 pages) | Cited 2 times

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This letter reports the time dependence of the surface Fermi level of GaAs grown by molecular‐beam epitaxy and then exposed to atmosphere. The sheet resistance of sample structures for field effect transistors alternately increased, decreased, increased, and decreased to become nearly constant after about 500 h. These changes correspond to the surface Fermi level varying between 0.3 and 0.7 eV and finally settling 0.7 eV above the valence band maximum. Comparison between annealed and unannealed samples with low‐temperature‐grown GaAs layers showed that the pinning of the surface Fermi level at 0.7 eV above the valence band maximum is caused by arsenic antisite defects. The result supports the advanced unified defect model.
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73.20.At Surface states, band structure, electron density of states
73.20.Hb Impurity and defect levels; energy states of adsorbed species

Single‐electron quantization of electric field domains in slim semiconductor superlattices

A. N. Korotkov, D. V. Averin, and K. K. Likharev

Appl. Phys. Lett. 62, 3282 (1993); http://dx.doi.org/10.1063/1.109100 (3 pages) | Cited 17 times

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It is shown that dc I‐V curves of the semiconductor superlattices of small (practically, submicron) cross section should exhibit oscillations with the dc voltage period e/C, where C is the capacitance between adjacent conducting layers. These oscillations are due to the single‐electron quantization of electric charge of the boundaries of static high‐electric‐field domains.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.40.Gk Tunneling
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Hydrogen passivation of grain boundary defects in polycrystalline silicon thin films

N. H. Nickel, N. M. Johnson, and W. B. Jackson

Appl. Phys. Lett. 62, 3285 (1993); http://dx.doi.org/10.1063/1.109101 (3 pages) | Cited 54 times

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The dependence of defect passivation in undoped polycrystalline silicon on hydrogenation conditions (i.e., time and temperature) was examined. At long hydrogenation times the spin density NS saturates. The saturation value of NS depends strongly on the hydrogenation temperature. The lowest residual spin density was obtained at 350 °C. Model calculations of the time and temperature dependence of the defect passivation suggest that the amount of hydrogen necessary for defect passivation exceeds the density of grain boundary defects by a factor that is significantly larger than unity and which depends on the hydrogenation temperature.
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71.55.Cn Elemental semiconductors
73.61.Cw Elemental semiconductors
61.72.Mm Grain and twin boundaries

Bistable opto‐optical switches with high optical gain based on n‐i‐p‐i doping superlattices

P. Kiesel, K. H. Gulden, A. Höfler, B. Knüpfer, M. Kneissl, P. Riel, G. H. Döhler, X. Wu, and J. S. Smith

Appl. Phys. Lett. 62, 3288 (1993); http://dx.doi.org/10.1063/1.109102 (3 pages) | Cited 8 times

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We report on optical logic gates and bistable opto‐optical switches with high gain operating at very low threshold power. These devices are ‘‘smart pixels’’ composed of n‐i‐p‐i threshold switches and modulators. Very high values of 3×105 for the opto‐optical gain (‘‘fan‐out’’) and extremely low switching powers of less than 500 pW in combination with a broad hysteresis width of 200 pW are obtained. The switching power, the width of the hysteresis, and the opto‐optical gain are all externally adjustable. The observed contrast ratio of 4.6 for the output signal corresponds to an optically induced voltage swing of 2.5 V.
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42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks
78.66.Fd III-V semiconductors

Si3N4/Si/In0.53Ga0.47As depletion‐mode metal‐insulator‐semiconductor field‐effect transistors with improved stability

D. S. L. Mui, Z. Wang, D. Biswas, A. L. Demirel, N. Teraguchi, J. Reed, and H. Morkoç

Appl. Phys. Lett. 62, 3291 (1993); http://dx.doi.org/10.1063/1.109075 (3 pages) | Cited 9 times

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We report on the electrical characteristics of in situ deposited Si3N4/Si/In0.53Ga0.47As depletion‐mode metal‐insulator‐semiconductor field‐effect transistors (MISFETs). MISFETs with 2.2‐μm gate lengths fabricated by a self‐aligned gate process exhibited extrinsic transconductances of over 200 mS/mm. The drain current drifted by only 1% during the first 10 h of operation. This small shift is attributed to the reduction of traps at the interface by a pseudomorphic Si layer, incorporated at the interface between the dielectric and the In0.53Ga0.47As channel.
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85.30.Tv Field effect devices
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.20.Hb Impurity and defect levels; energy states of adsorbed species

Dry lithography using focused ion beam implantation and reactive ion etching of SiO2

Kent D. Choquette and Lloyd R. Harriott

Appl. Phys. Lett. 62, 3294 (1993); http://dx.doi.org/10.1063/1.109623 (3 pages) | Cited 4 times

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We report a novel dry process suitable for submicron lithography using focused ion beam writing and plasma development of SiO2. Robust masks are fashioned in layers of SiO2 with a focused Ga ion beam, followed by development using CF4/O2 reactive ion etching. We find the development selectivity (etch rate ratio) between unimplanted and implanted SiO2 increases with increasing Ga dose. Using an implant dose of 1.5×1016 cm−2 we form SiO2 line and circular dot masks with dimensions as small as 300 nm. To demonstrate the utility of these durable masks, the patterns are transferred into GaAs by reactive ion etching, producing structures with aspect ratios (depth/width) greater than 10. Since masks formed of SiO2 are appropriate for ion bombardment processes such as found in plasma etching, as well as high‐temperature regrowth steps, this dry lithographic technique is promising for in situ vacuum integrated fabrication.
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85.40.Hp Lithography, masks and pattern transfer
81.65.-b Surface treatments
61.80.Jh Ion radiation effects
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