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30 Jun 1997

Volume 70, Issue 26, pp. 3489-3619

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Detecting squeezed phonons through an indirect radiative transition

Ö. E. Müstecaplıoglu and A. S. Shumovsky

Appl. Phys. Lett. 70, 3489 (1997); http://dx.doi.org/10.1063/1.119209 (3 pages) | Cited 1 time

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A model of the effect of the longitudinal optical phonon number distribution on the Rabi oscillations of the photons involved in the associated indirect transition in a semiconductor is presented. It is shown that a faster cavity photon revival rate is obtained given an initial squeezed thermal phonon state. This is the result of pairwise correlations of phonons due to squeezing and also holds true when phonons are in squeezed vacuum or in squeezed number states. It may be possible to use this effect to detect squeezing in phonons. © 1997 American Institute of Physics.
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42.50.Dv Quantum state engineering and measurements
42.50.Ct Quantum description of interaction of light and matter; related experiments
63.20.D- Phonon states and bands, normal modes, and phonon dispersion

Growth and ultraviolet application of Li2B4O7 crystals: Generation of the fourth and fifth harmonics of Nd:Y3Al5O12 lasers

R. Komatsu, T. Sugawara, K. Sassa, N. Sarukura, Z. Liu, S. Izumida, Y. Segawa, S. Uda, T. Fukuda, and K. Yamanouchi

Appl. Phys. Lett. 70, 3492 (1997); http://dx.doi.org/10.1063/1.119210 (3 pages) | Cited 58 times

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A 2 in. diam single crystal of lithium tetraborate (Li2B4O7) was successfully grown by the Czochralski method. The crystal was free from macrodefects and had a dislocation density as low as 100/cm2. It had an excellent homogeneity of the refractive index and a wide transparency down to 170 nm. The optical damage threshold was 40 GW/cm2. Second-harmonic generation and sum frequency generation were investigated in association with the generation of the fourth and fifth harmonics of a Q-switched Nd:YAG laser. The conversion efficiency of the second-harmonic generation from the green (532 nm) light was 20%. © 1997 American Institute of Physics.
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42.70.Hj Laser materials
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.55.Rz Doped-insulator lasers and other solid state lasers

Strong pyroelectric response in semiconducting Y-Ba-Cu-O and its application to uncooled infrared detection

A. Jahanzeb, C. M. Travers, D. P. Butler, Z. Çelik-Butler, and J. E. Gray

Appl. Phys. Lett. 70, 3495 (1997); http://dx.doi.org/10.1063/1.119211 (3 pages) | Cited 11 times

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A pyroelectric infrared detector operating at room temperature and based on semiconducting Y-Ba-Cu-O was fabricated. The capacitor structure consisting of semiconducting Y-Ba-Cu-O layer sandwiched between two Nb electrodes was fabricated on top of a thermally isolated SiO2 bridge. The polycrystalline Y-Ba-Cu-O layer was deposited by ambient-temperature sputtering while standard Si micromachining techniques were used to etch the silicon under the oxide bridge. The pyroelectric response of the material is characterized by the temperature coefficient of polarization (p = dP/dT) which was measured to be as high as 65 nC/K cm2 without an externally applied electric field. The pyroelectric figure of merit Fd for the material was estimated to be 0.032 (cm3/J)1/2. Employing a radiometric infrared source, the room-temperature voltage responsivity RV and specific detectivity D∗ of the unbiased detector were measured to be over 103 V/W and 108 cm Hz1/2/W, respectively. This letter discusses the characteristics of this complementary metal-oxide semiconductor-compatible pyroelectric detector and suggests methods for the improvement for its figures of performance. © 1997 American Institute of Physics.
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77.70.+a Pyroelectric and electrocaloric effects
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors

Ultrafast all-optical gate switch based on frequency shift accompanied by semiconductor band-filling effect

Shigeru Nakamura and Kazuhito Tajima

Appl. Phys. Lett. 70, 3498 (1997); http://dx.doi.org/10.1063/1.119212 (3 pages) | Cited 13 times

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We propose a novel all-optical gate switch based on a frequency shift accompanied by the semiconductor band-filling effect. This all-optical switch is very simple in structure, yet is capable of ultra-high-speed and high-efficiency switching. The switching characteristics are numerically investigated with a rate equation model for nonlinear phase shift. Then, the principle of operation is experimentally verified by measuring the spectral and time-domain properties of the switch. Its switching time is nearly the same as the duration (600 fs in the present experiment) of a control pulse. © 1997 American Institute of Physics.
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42.79.Sz Optical communication systems, multiplexers, and demultiplexers
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Active mode locking with a hybrid neodymium laser

Li Yan and Bo Guo

Appl. Phys. Lett. 70, 3501 (1997); http://dx.doi.org/10.1063/1.119213 (3 pages) | Cited 2 times

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A novel concept of mode locking with a hybrid laser was demonstrated in an actively mode-locked hybrid neodymium (Nd) laser, which contains both Nd:YLF and Nd:glass in a single cavity. A small gain from Nd:YLF can control the spectrum of Nd:glass and ensure good phase coherence among the lasing axial modes, generating stable, coherent pulses of 11 ps. The broadband Nd:glass can facilitate spectral broadening and produce shorter pulses than by Nd:YLF alone under the same mode-locking force. © 1997 American Institute of Physics.
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42.60.Fc Modulation, tuning, and mode locking
42.55.Rz Doped-insulator lasers and other solid state lasers

Reduction of light-scattering loss in silica glass by the structural relaxation of “frozen-in” density fluctuations

K. Saito and A. J. Ikushima

Appl. Phys. Lett. 70, 3504 (1997); http://dx.doi.org/10.1063/1.119214 (3 pages) | Cited 15 times

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Temperature dependences of light-scattering intensity in silica glasses were measured over a wide temperature range from 300 to 1 900 K. It was found that in OH-free silica glass, the diffusive density fluctuations are completely “frozen-in” at the glass transition temperature, while in OH-containing glass, OH gives rise to the structural relaxation of these “frozen-in” density fluctuations over 400 K below the glass transition temperature. This structural relaxation, expected to be caused by the introduction of some dopants with the same role of OH, can be used for reduction of the light-scattering loss in silica fibers. © 1997 American Institute of Physics.
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42.81.Dp Propagation, scattering, and losses; solitons
42.70.Ce Glasses, quartz
78.35.+c Brillouin and Rayleigh scattering; other light scattering

Interference scanning optical probe microscopy

W. S. Bacsa and A. Kulik

Appl. Phys. Lett. 70, 3507 (1997); http://dx.doi.org/10.1063/1.119215 (3 pages) | Cited 5 times

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We describe an optical scanning probe technique (Interference Scanning Optical Probe Microscopy) with enhanced resolution possibilities not limited by the aperture size of the optical probe. This is realized using a substrate in the form of a microcavity and probe collection mode in reflection geometry. The microcavity consisting of an opaque and a transparent layer, is used to shift the phase of the wave scattered from the adsorbate with respect to the incident and reflected beams. Using this technique silver island films have been detected with resolution better than 40 nm with a nominal probe aperture size of 100 nm. © 1997 American Institute of Physics.
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07.79.-v Scanning probe microscopes and components
68.35.B- Structure of clean surfaces (and surface reconstruction)
42.30.-d Imaging and optical processing

Dynamic polariscopic imaging of laser-induced strain in a tissue phantom

G. Delacrétaz, J. T. Walsh, and T. Asshauer

Appl. Phys. Lett. 70, 3510 (1997); http://dx.doi.org/10.1063/1.119216 (3 pages) | Cited 3 times

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Laser ablation and associated bubble formation are known to damage biologic tissue. Imaging of tissue straining during ablation would further the understanding and control of laser-induced damage. We have investigated the use of polariscopic imaging to monitor the strain induced by holmium laser radiation. The laser energy was delivered via an optical fiber either within or 1.7 mm from the surface of a photoelastic tissue phantom, poly(acrylamide) gel, whose viscoelastic properties could be controlled to mimic various tissues. Our results demonstrate that dynamic polaroscopy is a sensitive method to probe the strain experienced by the tissue during pulsed laser irradiations. Only compressive strain is observed when the bubble is formed within the phantom, whereas significant tensile strain is induced when the bubble is formed at or next to the surface. © 1997 American Institute of Physics.
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87.50.W- Optical/infrared radiation effects
87.64.-t Spectroscopic and microscopic techniques in biophysics and medical physics
07.60.Fs Polarimeters and ellipsometers

Ordering temperatures in Cu–Al–Ni shape memory alloys

V. Recarte, O. A. Lambri, R. B. Pérez-Sáez, M. L. Nó, and J. San Juan

Appl. Phys. Lett. 70, 3513 (1997); http://dx.doi.org/10.1063/1.119217 (3 pages) | Cited 20 times

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The ordering temperatures Tc1 (disordered β to B2 order) and Tc2 (B2 to L21 order) have been obtained in Cu–Al–Ni shape memory alloys with different concentrations by electrical resistivity. The dependence of the ordering temperatures on the concentration has been established. Also, a modification of the theoretical calculations has been proposed to predict the ordering temperatures in Cu–Al–Ni ternary alloys. A good agreement between the theoretical ordering temperatures and the experimental results has been found. © 1997 American Institute of Physics.
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81.30.Kf Martensitic transformations
81.05.Bx Metals, semimetals, and alloys
72.15.Eb Electrical and thermal conduction in crystalline metals and alloys

Highly textured and conductive undoped ZnO film using hydrogen post-treatment

Seung Jae Baik, Jae Hoon Jang, Chang Hyun Lee, Woo Yeong Cho, and Koeng Su Lim

Appl. Phys. Lett. 70, 3516 (1997); http://dx.doi.org/10.1063/1.119218 (3 pages) | Cited 50 times

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We proposed a method to enhance the characteristics of undoped ZnO films by H2 post-treatment using photochemical vapor deposition. The resistivity of a H2-treated film decreased from 1×10−2 to 2×10−3 Ω cm, the haze ratio increased from 37% to 48%, and no degradation of total transmittance was observed. There are two possible explanations for these phenomena. First, hydrogen atoms assist the desorption of oxygen atoms from the film, resulting in decreased resistivity. Second, hydrogen atoms etch small grains growing among large ones on the surface of the film, resulting in a rough surface. © 1997 American Institute of Physics.  
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73.61.Ga II-VI semiconductors
68.55.-a Thin film structure and morphology
81.65.Cf Surface cleaning, etching, patterning

A lower bound on implant density to induce wafer splitting in forming compliant substrate structures

L. B. Freund

Appl. Phys. Lett. 70, 3519 (1997); http://dx.doi.org/10.1063/1.119219 (3 pages) | Cited 47 times

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The physical system under study is a bonded semiconductor wafer into which hydrogen ions have been implanted within a planar zone, typical of a configuration used in forming semiconductor-on-insulator compliant substrates by wafer splitting. Under the assumption that splitting is a consequence of crack growth driven by hydrogen gas pressure, a lower bound estimate of the implant density required for large area crack growth is obtained which, for an ideal gas, depends only on the cohesive strength of the material and on temperature. © 1997 American Institute of Physics.
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85.40.Ry Impurity doping, diffusion and ion implantation technology
68.35.Fx Diffusion; interface formation
81.05.Cy Elemental semiconductors

Oxygen surface diffusion in three-dimensional Cu2O growth on Cu(001) thin films

J. C. Yang, M. Yeadon, B. Kolasa, and J. M. Gibson

Appl. Phys. Lett. 70, 3522 (1997); http://dx.doi.org/10.1063/1.119220 (3 pages) | Cited 39 times

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By studying the growth of Cu2O islands during the initial oxidation stage of Cu(001) with in situ transmission electron microscopy, it is found that the dominant mechanism for the growth of three-dimensional islands is surface diffusion of oxygen. However, there exists a non-negligible contribution to the metal oxide growth by another mechanism, probably direct impingement of the oxygen atoms on the oxide island. These results demonstrate the importance of surface conditions in oxidation. © 1997 American Institute of Physics.
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68.35.Fx Diffusion; interface formation
68.55.-a Thin film structure and morphology
81.65.Mq Oxidation
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)

The dissolution behavior of the void defects by hydrogen annealing in Czochralski grown silicon crystals

K. Nakamura, T. Saishoji, and J. Tomioka

Appl. Phys. Lett. 70, 3525 (1997); http://dx.doi.org/10.1063/1.119221 (3 pages) | Cited 2 times

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The annihilation of grown-in defects by hydrogen annealing have been explained as the dissolution of oxygen precipitates, because it has been generally thought that grown-in defects in Czochralski silicon crystals are gigantic oxygen precipitates. However, it is necessary to re-examine the mechanism of the annihilation of the defects by hydrogen annealing, because recently it has been shown that the grown-in defects were voids of octahedral shape. In this letter, a simulation model is presented which describes the annihilation process of void defects by hydrogen annealing. © 1997 American Institute of Physics.
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61.72.Cc Kinetics of defect formation and annealing
61.72.Qq Microscopic defects (voids, inclusions, etc.)

Threshold behavior in synchrotron-radiation-stimulated recrystallization during Si homoepitaxy on Si(100)

Housei Akazawa

Appl. Phys. Lett. 70, 3528 (1997); http://dx.doi.org/10.1063/1.119222 (3 pages) | Cited 3 times

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A brilliant synchrotron-radiation beam with a large irradiation area has made it possible to use spectroscopic phase-modulated ellipsometry to monitor vacuum-ultraviolet-excited Si homoepitaxy. We find the crystallinity of Si films grown at 250 °C from Si2H6 depends strongly on the photon intensity. When the photon intensity is higher than a critical value, electronically excited crystallization yields epitaxial Si. At lower intensities, however, the initial epitaxy is terminated halfway by island-shaped regions of polycrystalline Si, which are eventually covered by a uniform nanocrystalline Si overlayer. © 1997 American Institute of Physics.
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64.70.K- Solid-solid transitions
61.80.Cb X-ray effects
68.55.-a Thin film structure and morphology

Density and structural changes in SiC after amorphization and annealing

V. Heera, F. Prokert, N. Schell, H. Seifarth, W. Fukarek, M. Voelskow, and W. Skorupa

Appl. Phys. Lett. 70, 3531 (1997); http://dx.doi.org/10.1063/1.119223 (3 pages) | Cited 27 times

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The density of amorphous SiC layers formed by 2 MeV Si+ implantation into single-crystalline 6H–SiC was measured by x-ray reflectometry and compared with the results of step height measurements. Reactive ion etching was used to investigate the density as a function of depth. The density of the as-amorphized SiC is about 12% less than that of the crystalline material. Within experimental accuracy, the density reduction is homogeneous across the whole layer thickness. Low-temperature annealing leads to the formation of relaxed amorphous SiC with a density about 7% below the crystalline one. These large density changes are in contrast to results in amorphous Si. They can be explained by the high atomic density of SiC and the chemical disorder in the amorphous state of SiC. © 1997 American Institute of Physics.
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61.72.up Other materials
61.43.Dq Amorphous semiconductors, metals, and alloys
61.05.cm X-ray reflectometry (surfaces, interfaces, films)

Theoretical investigation on δ doping of Se atoms in GaAs

Jun Nara, Taizo Sasaki, and Takahisa Ohno

Appl. Phys. Lett. 70, 3534 (1997); http://dx.doi.org/10.1063/1.119224 (3 pages)

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We report the result of first-principles calculations on Se δ-doped GaAs and propose a carrier compensation mechanism in the region of high Se concentrations. It is found that introducing Ga vacancies near Se atoms makes the system extremely stable and semiconducting. In the high-concentration region where Se atoms are close to each other, the Se atoms are likely to get together by introducing Ga vacancies and form clusters consisting of three Se atoms and one Ga vacancy. The extra electrons of the Se atoms transfer to the dangling bonds of the Se or As atoms, and become electrically inactive. © 1997 American Institute of Physics.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.uj III-V and II-VI semiconductors

Effect of irradiant wavelength during porous silicon formation

Crona Malone and Jacob Jorne

Appl. Phys. Lett. 70, 3537 (1997); http://dx.doi.org/10.1063/1.119225 (3 pages) | Cited 2 times

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Photoelectrochemical etching of silicon using light assistance of various wavelengths has been studied. As the etching process proceeds, a blueshift is noted in the photoluminescence spectra. However, after a certain period of etching, under a fixed current density, a saturation point is reached, below which no further shift to higher energies is detected. This cutoff point occurs at approximately 2 eV, even if a much higher energy irradiant light source is used during the formation process. These results provide strong evidence for the surface-state mechanism of luminescence and render the pure quantum confinement model unlikely. © 1997 American Institute of Physics.
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78.55.Mb Porous materials
81.65.Cf Surface cleaning, etching, patterning
81.05.Cy Elemental semiconductors

Optical absorption edge of semi-insulating GaAs and InP at high temperatures

M. Beaudoin, A. J. G. DeVries, S. R. Johnson, H. Laman, and T. Tiedje

Appl. Phys. Lett. 70, 3540 (1997); http://dx.doi.org/10.1063/1.119226 (3 pages) | Cited 39 times

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The temperature dependences of the optical absorption edges of semi-insulating GaAs and InP have been measured from room temperature to 905 °C and 748 °C, respectively, with accuracies of ±1 °C at room temperature and ±5 °C at 900 °C. The temperature dependence of the optical absorption edge is adequately reproduced by an Einstein model although the Varshni model gives an improved fit to the band gap. Finally, the widths of the absorption edges are correlated with ionicity. © 1997 American Institute of Physics.
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78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
07.20.Dt Thermometers
81.05.Ea III-V semiconductors

Near-infrared sideband generation induced by intense far-infrared radiation in GaAs quantum wells

J. Černe, J. Kono, T. Inoshita, M. Sherwin, M. Sundaram, and A. C. Gossard

Appl. Phys. Lett. 70, 3543 (1997); http://dx.doi.org/10.1063/1.119227 (3 pages) | Cited 38 times

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GaAs quantum wells are simultaneously illuminated with near-infrared (NIR) radiation at frequency ωnir and intense far-infrared (FIR) radiation from a free-electron laser at ωfir. Magnetic fields up to 9 T are applied. Strong and narrow sidebands are observed at ωsideband = ωnir±2ωfir. The intensity of the sidebands is enhanced when either ωsideband or ωnir is near the onset of NIR absorption in the quantum well, or when ωfir is near the free-electron cyclotron frequency. We attribute these sidebands to four-wave mixing of NIR and FIR photons whose energies differ by more than a factor of 100. © 1997 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.30.Fs III-V and II-VI semiconductors
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
78.20.Ls Magneto-optical effects

Sequential tunneling current through semiconductor superlattices under intense THz radiation

Gloria Platero and Ramón Aguado

Appl. Phys. Lett. 70, 3546 (1997); http://dx.doi.org/10.1063/1.119228 (3 pages) | Cited 25 times

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Recent transport measurements in GaAs–GaAlAs superlattices under THz radiation show evidence of dynamical localization and electron pumping in the opposite direction to the dc bias in the linear response regime. The ac field induces absorption and emission processes in the multiwell structure which assist the tunnel and which are reflected as new features in the current density. A calculation within the framework of the Bardeen Hamiltonian has been performed to evaluate the tunneling current through the superlattice in the presence of an ac field. By means of this model these new features are reproduced in the current which can be explained in terms of the new induced tunneling channels and of the charge occupation in the wells. © 1997 American Institute of Physics.
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73.40.Gk Tunneling

Influence of growth conditions on electrical characteristics of AlN on SiC

C.-M. Zetterling, M. Östling, N. Nordell, O. Schön, and M. Deschler

Appl. Phys. Lett. 70, 3549 (1997); http://dx.doi.org/10.1063/1.119229 (3 pages) | Cited 12 times

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Undoped aluminum nitride films were grown on 4H or 6H silicon carbide substrates, using metal–organic chemical-vapor deposition at 1150 °C. Different growth conditions were used, and two different V/III ratios were tested. Metal–insulator–semiconductor capacitors were made for high-frequency capacitance–voltage measurements at room temperature, from which the film thickness was determined. Accumulation, depletion, deep depletion, and inversion were seen for the best films, which also displayed peaks in x-ray diffraction rocking curves. Although large flatband voltage shifts occurred, indicating a fixed charge and interface trap problem, low conductance was observed. A flow of ammonia during ramp-up was found to improve the AlN films. © 1997 American Institute of Physics.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.61.Ey III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

New ripple patterns observed in excimer-laser irradiated SiO2/polycrystalline silicon/SiO2 structures

G. K. Giust and T. W. Sigmon

Appl. Phys. Lett. 70, 3552 (1997); http://dx.doi.org/10.1063/1.119230 (3 pages) | Cited 9 times

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A new ripple formation mechanism is observed in excimer-laser irradiated polycrystalline silicon (polysilicon) films on oxidized silicon wafers. The ripples form for polysilicon films capped with a thin oxide, and for laser fluences that completely melt the buried polysilicon. The resulting ripples are unlike those previously reported in that (1) their wavelength cannot be predicted by Rayleigh’s diffraction condition, (2) their wave fronts are arranged in chaotic patterns, rather than parallel lines, and (3) the wave fronts can be manipulated by changing the polysilicon surface topology. The characteristics of these ripples are investigated in the context of understanding the underlying physics. © 1997 American Institute of Physics.
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61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
81.40.Wx Radiation treatment (particle and electromagnetic)
64.70.D- Solid-liquid transitions

Near-field scanning optical microscopy studies of Cu(In,Ga)Se2 solar cells

A. A. McDaniel, J. W. P. Hsu, and A. M. Gabor

Appl. Phys. Lett. 70, 3555 (1997); http://dx.doi.org/10.1063/1.119231 (3 pages) | Cited 5 times

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A near-field scanning optical microscope (NSOM) is used to study the local photoresponse of Cu(In,Ga)Se2 thin film solar cells. The grain boundaries of the small grains (<1 μm) show some reduction in photoresponse; however the photoresponse is significantly reduced near most crevices separating large grains (>10 μm). In addition, NSOM images show response variations from grain to grain and areas of reduced photoresponse which have no corresponding topography. Photovoltage imaging of the cleaved side of the solar cells reveals the depth and nonuniformities of the actual p-n junction. It is found that the response of the p-n junction varies on a 0.5 μm length scale. © 1997 American Institute of Physics.
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84.60.Jt Photoelectric conversion
07.79.Fc Near-field scanning optical microscopes
72.40.+w Photoconduction and photovoltaic effects

Band gaps of GaPN and GaAsN alloys

L. Bellaiche, S.-H. Wei, and Alex Zunger

Appl. Phys. Lett. 70, 3558 (1997); http://dx.doi.org/10.1063/1.119232 (3 pages) | Cited 92 times

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The importance of atomic relaxations, chemical disorder, and epitaxial constraints on the band gap of random, anion-mixed nitride alloys GaPN and GaAsN have been investigated, via pseudopotentials calculation. It has been demonstrated that simple approximations such as the virtual crystal approximation, or the use of high-symmetry ordered structure to mimic a random alloy, or the neglect of atomic displacements, are inadequate. It is found that a fully relaxed, large supercell calculation reproduces well the experimental band gaps of GaPN and GaAsN films. © 1997 American Institute of Physics.
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71.20.Nr Semiconductor compounds
71.15.Dx Computational methodology (Brillouin zone sampling, iterative diagonalization, pseudopotential construction)
71.55.Eq III-V semiconductors

Synthesis and control of conductivity of ultraviolet transmitting β-Ga2O3 single crystals

Naoyuki Ueda, Hideo Hosono, Ryuta Waseda, and Hiroshi Kawazoe

Appl. Phys. Lett. 70, 3561 (1997); http://dx.doi.org/10.1063/1.119233 (3 pages) | Cited 80 times

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β-Ga2O3 single crystals were grown by the floating zone method and their conductivity along the b axis was controlled from <10−9 to 38 Ω−1 cm−1 by changing the growth atmosphere. By using feed rods doped with Sn, the grown crystal became highly conductive even under oxidative atmosphere. The optical transmission spectra showed that the β-Ga2O3 single crystal with 0.32 mm was transparent in the visible and ultraviolet region, with 20% transmittance at the fourth-harmonic wave of the Nd:YAG laser (266 nm). The band-gap widening was observed with the increasing of the carrier concentration. It is expected that the light of the KrF laser can be transmitted in the heavily doped β-Ga2O3.© 1997 American Institute of Physics.
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72.80.Jc Other crystalline inorganic semiconductors
78.40.Ha Other nonmetallic inorganics
81.05.Hd Other semiconductors
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