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15 Jul 1991

Volume 59, Issue 3, pp. 253-375

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1.55 μm buried heterostructure laser via regrowth of semi‐insulating InP:Fe around vertical mesas fabricated by reactive ion etching using methane and hydrogen

O. Kjebon, S. Lourdudoss, B. Hammarlund, S. Lindgren, M. Rask, P. Ojala, G. Landgren, and B. Broberg

Appl. Phys. Lett. 59, 253 (1991); http://dx.doi.org/10.1063/1.105612 (3 pages) | Cited 17 times

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A GaInAsP/InP Fabry–Perot‐type buried‐heterostructure quantum well laser operating at 1.55 μm has been realized utilizing iron‐doped semi‐insulating InP around vertical mesas fabricated by reactive ion etching using methane and hydrogen. A maximum cw output power of 19 mW has been achieved on as‐cleaved chips of 300 μm length with a quantum efficiency of 21% per facet. Threshold currents lie between 20 and 25 mA. As low as 2 Ω series resistance has been measured despite an ohmic contact area not exceeding that of the 2‐μm‐wide mesa. A 3 dB bandwidth of 7.5 GHz at 12 mW output power is obtained from the small‐signal frequency modulation measurements.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
81.15.Kk Vapor phase epitaxy; growth from vapor phase
73.61.Ey III-V semiconductors

Two‐wave mixing in photorefractive AlGaAs/GaAs quantum wells

Q. N. Wang, D. D. Nolte, and M. R. Melloch

Appl. Phys. Lett. 59, 256 (1991); http://dx.doi.org/10.1063/1.105613 (3 pages) | Cited 27 times

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We have observed two‐wave mixing in semi‐insulating AlGaAs/GaAs multiple quantum well structures at wavelengths near the exciton absorption. The photorefractive index changes are caused by the Franz–Keldysh effect on quantum‐confined excitons. Photorefractive gains larger than 200 cm−1 are obtained for the first time at wavelengths near 836 nm using stationary fringes and dc applied fields up to 5 kV/cm. The direction of energy transfer between the two beams is determined by the direction of applied electric field.
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78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
78.20.Jq Electro-optical effects
42.79.Hp Optical processors, correlators, and modulators

Comparison of optical nonlinearities of type II and type I quantum wells

K. Meissner, B. Fluegel, R. Binder, S. W. Koch, G. Khitrova, and N. Peygambarian

Appl. Phys. Lett. 59, 259 (1991); http://dx.doi.org/10.1063/1.105614 (3 pages) | Cited 4 times

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We have performed low‐temperature femtosecond pump and probe experiments on GaAs/AlAs type II and GaAs/AlGaAs type I multiple quantum wells of similar well sizes. The measurements are analyzed using a many‐body theory appropriate for both types of systems. It is found that the type I and type II nonlinearities are very similar at early times after excitation. However, the very fast (<1 ps) Γ to X electron scattering in the type II samples causes pronounced differences at later times, allowing the observation of hole relaxation in the type II samples.
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78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Log‐periodic antennas for pulsed terahertz radiation

D. R. Dykaar, B. I. Greene, J. F. Federici, A. F. J. Levi, L. N. Pfeiffer, and R. F. Kopf

Appl. Phys. Lett. 59, 262 (1991); http://dx.doi.org/10.1063/1.105615 (3 pages) | Cited 15 times

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A new type of log‐periodic antenna, the wire log‐spiral, has been designed and implemented on GaAs substrates with low‐temperature grown GaAs photoconductors. The new antenna is compared to two traditional antenna designs (log‐periodic and dipole) used for the detection of pulsed THz radiation.
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84.40.Az Waveguides, transmission lines, striplines
84.40.Ba Antennas: theory, components and accessories

Ohmic heating and series resistance of a vertical‐microcavity surface‐emitting laser

Guotong Du, J. Lin, J. K. Gamelin, B. Wu, J. J. Talghader, S. Wang, Y. J. Yang, T. G. Dziura, and S. C. Wang

Appl. Phys. Lett. 59, 265 (1991); http://dx.doi.org/10.1063/1.105616 (3 pages) | Cited 3 times

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We report the results of investigations on the transient heating and series resistance of a vertical‐microcavity surface‐emitting (VMSE) laser with an air‐bridge structure. Transient temperature broadening of the lasing spectrum and chirping of the current versus voltage characteristic are analyzed experimentally and theoretically. We believe that the experiments provide us valuable information on the severity of the heating problems in VMSE laser.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.79.Sz Optical communication systems, multiplexers, and demultiplexers

High‐speed InP/GaInAs heterojunction phototransistor on InP‐on‐Si grown by organometallic vapor phase epitaxy

O. Aina, M. Serio, M. Mattingly, J. O’Connor, S. K. Shastry, D. S. Hill, J. P. Salerno, and P. Ferm

Appl. Phys. Lett. 59, 268 (1991); http://dx.doi.org/10.1063/1.105617 (3 pages) | Cited 1 time

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We have fabricated the first heterojunction phototransistor (HPT) on InP‐on‐Si. These phototransistors, based on the InP/GaInAs heterojunction, have optical gains as high as 125 A/W at 1300 nm and dark currents as low as 300 pA, for a 48×64 μm HPT. The bandwidth was determined from impulse photoresponse measurements to be 4.4 GHz. The intrinsic bandwidth was estimated from the zero bias capacitance (0.2 pf) to be as high as 16 GHz.
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85.60.Dw Photodiodes; phototransistors; photoresistors
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Laser‐induced fluorescence studies of pulsed uranium ablation by a Nd:YAG Q‐switched laser

Jianan Qu, Zhiyao Zhou, Lizhou Zhu, and Fucheng Lin

Appl. Phys. Lett. 59, 271 (1991); http://dx.doi.org/10.1063/1.105618 (3 pages) | Cited 2 times

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A high‐resolution laser spectroscopy method is used to analyze the time‐of‐flight (TOF) distribution of uranium atoms photoablated by a Nd:YAG Q‐switched laser in real time. The velocity distribution of an individual pulsed beam of ablated particles was derived from the TOF spectrum. The velocity of the neutral atoms ranged from 1 to 10 km/s in our experiments.
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61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
79.20.Ds Laser-beam impact phenomena
64.70.Hz Solid-vapor transitions

Secondary cavitation due to interaction of a collapsing bubble with a rising free surface

Y. Tomita, T. Kodama, and A. Shima

Appl. Phys. Lett. 59, 274 (1991); http://dx.doi.org/10.1063/1.105619 (3 pages) | Cited 12 times

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An experimental investigation was made of the motion of a cavitation bubble in the vicinity of a free surface in order to study an induced secondary cavitation during the bubble rebound. A bubble was produced by focusing a ruby laser into water, and its subsequent behavior was observed with a high‐speed camera. The deformable nature of both a bubble and a free surface becomes significant as the mutual distance between them is decreased. Immediately after bubble rebound, a secondary cavitation occurs at around zero dynamic pressure region which is developed in water between a rising free surface and a collapsing bubble, due to the local pressure reduction mainly caused by the interaction of expansion waves originated from the surface.
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47.55.dp Cavitation and boiling
42.55.Mv Dye lasers
43.25.Yw Nonlinear acoustics of bubbly liquids

Simulations of high‐rate diamond synthesis: Methyl as growth species

D. G. Goodwin

Appl. Phys. Lett. 59, 277 (1991); http://dx.doi.org/10.1063/1.105620 (3 pages) | Cited 91 times

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The results of numerical simulations of two high‐rate diamond growth environments (oxygen‐acetylene torch and dc arcjet) are reported. The calculations account in detail for boundary‐layer transport, gas‐phase chemistry, and gas‐surface chemistry. Diamond growth rates are calculated self‐consistently with the gas‐phase concentrations, using a recently proposed methyl growth mechanism. The calculated growth rates agree well with the measured values, indicating that this growth mechanism can account for both high‐ and low‐rate diamond growth.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
82.20.Wt Computational modeling; simulation
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Comparative study of the properties of ultrathin Si3N4 films with Auger electron spectroscopy, spectroscopic ellipsometry, and Raman spectroscopy

E. C. Paloura, S. Logothetidis, S. Boultadakis, and S. Ves

Appl. Phys. Lett. 59, 280 (1991); http://dx.doi.org/10.1063/1.105621 (3 pages) | Cited 10 times

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Ultrathin Si3N4 films are characterized with Auger electron spectroscopy, spectroscopic ellipsometry (SE), and Raman spectroscopy (RS). It is shown that Ar+ sputtering induces preferential nitrogen sputtering which causes problems in the determination of the interface location. Film thickness measurements with the nondestructive SE technique result in film thicknesses systematically larger than those calculated from the Auger sputter profiling, for films thinner than 100 Å. Furthermore, analysis of the SE and RS data shows that the films are dense and stoichiometric while the stress induced by the Si3N4 film on the Si substrate amounts to 2–3 kbar.
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68.55.-a Thin film structure and morphology
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
77.55.-g Dielectric thin films

High quality thin gate oxide prepared by annealing low‐pressure chemical vapor deposited SiO2 in N2O

J. Ahn, W. Ting, T. Chu, S. Lin, and D. L. Kwong

Appl. Phys. Lett. 59, 283 (1991); http://dx.doi.org/10.1063/1.105622 (3 pages) | Cited 16 times

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In this letter, the electrical properties of thin low‐pressure chemical vapor deposited (LPCVD) SiO2 annealed in N2O ambient have been studied and compared with thermal oxide of identical thickness. It is shown that N2O‐annealed CVD oxide exhibits less interface state generation and less flatband voltage shift under constant current stress than thermal oxide. It also has excellent uniformity and comparable breakdown characteristics. An oxynitride film formation at the Si/SiO2 interface by annealing in N2O is speculated to be the cause of these improvements.
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81.65.-b Surface treatments
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Self‐aligned technology for tungsten‐contacted InP‐based etched mesa laser devices

A. Katz, S. J. Pearton, and M. Geva

Appl. Phys. Lett. 59, 286 (1991); http://dx.doi.org/10.1063/1.105599 (3 pages) | Cited 16 times

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The characteristics of W metallization for use as self‐aligned ohmic contacts and selective area etching and regrowth masks on InP‐based laser structures are reported. rf‐sputtered W films under either compressive or tensile stress were examined. Mesas for epitaxial regrowth were obtained by CF4/O2 dry etching of the previously deposited W film, followed either by HBr/H2O2/H2O wet chemical etching or CH4/H2/Ar electron cyclotron resonance plasma etching of ∼4 μm of InP. The W film preserved its inert metallurgical nature while heated under PH3/H2 ambient at 700 °C for 20 min, simulating the standard regrowth conditions. The W contacts on n‐InP (n=5×1018 cm−3) substrates yielded stable, low contact resistivity (0.2 Ω cm) after rapid thermal processing at 600–700 °C.
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73.40.Cg Contact resistance, contact potential
72.80.Ey III-V and II-VI semiconductors

Effects of sputter gas medium on the nanometer‐scale surface structures of the Pt/Co multilayers

S. L. Tang, P. F. Carcia, A. J. McGhie, and E. B. James

Appl. Phys. Lett. 59, 289 (1991); http://dx.doi.org/10.1063/1.105600 (3 pages) | Cited 4 times

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The surface structure of polycrystalline Pt/Co multilayer thin films, sputter‐deposited on glass substrates with Ar, Kr, or Xe, was obtained with near‐atom resolution by scanning tunneling microscopy. Monatomic steps separating narrow terraces on the Ar‐sputtered films and large step‐like structures on the order of the Pt/Co bilayer thickness on the Xe‐sputtered films were observed. We attributed differences in surface features to bombardment of the growing film surface by reflected neutral inert gas atoms with different energy distributions. We correlated the observed surface structures with magnetic coercivity of these films.
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68.55.-a Thin film structure and morphology
81.15.Cd Deposition by sputtering
75.70.Ak Magnetic properties of monolayers and thin films
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination

In situ determination of phosphorus composition in GaAs1−xPx grown by gas‐source molecular beam epitaxy

H. Q. Hou, B. W. Liang, T. P. Chin, and C. W. Tu

Appl. Phys. Lett. 59, 292 (1991); http://dx.doi.org/10.1063/1.105601 (3 pages) | Cited 15 times

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We report for the first time an in situ determination of phosphorus compositions in a mixed group‐V compound, such as GaAs1−xPx, grown by gas‐source molecular beam epitaxy. Reflection high‐energy electron diffraction intensity oscillations from As‐limited and (As+P)‐limited growth are observed on a Ga‐rich GaAs surface. The phosphorus composition is therefore deduced from the different growth rates. Viability of this technique is strongly confirmed by the good agreement with the phosphorus compositions determined ex situ by x‐ray rocking curve measurements on GaAs/GaAsP strained‐layer superlattice structures.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.Nq Composition and phase identification
61.05.C- X-ray diffraction and scattering

Scanning tunneling microscopy on chemical vapor deposited diamond films

H.‐G. Busmann, H. Sprang, I. V. Hertel, W. Zimmermann‐Edling, and H.‐J. Güntherodt

Appl. Phys. Lett. 59, 295 (1991); http://dx.doi.org/10.1063/1.105602 (3 pages) | Cited 25 times

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We have studied chemical vapor deposited diamond films by scanning tunneling microscopy. The films have been prepared in a hot‐filament reactor. The gas, a mixture of 1% methane and 99% hydrogen, is fed into the reactor by a pulsed high pressure valve. Growth rates of 1.5 μm/h were obtained. The films are defined by scanning electron microscopy (SEM), Raman spectroscopy, and x‐ray diffraction. On a scale similar to those normally found in SEM micrographs a 110 texture is shown. On smaller scales amorphous structures with typical sizes less than 100 nm and individual equally sized clusters of approximately 5 nm in diameter are observed.
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68.55.-a Thin film structure and morphology
81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination

Transistor action based on field‐effect controlled current injection into an insulator/SrTiO3 interface

Hirotaka Tamura, Akira Yoshida, and Shinya Hasuo

Appl. Phys. Lett. 59, 298 (1991); http://dx.doi.org/10.1063/1.105576 (3 pages) | Cited 9 times

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Transistor action with both voltage and current gain exceeding 1 was observed in structures consisting of metal electrodes, insulating barriers, and high‐dielectric‐constant insulating SrTiO3. These structures were made on insulating (100) single‐crystal SrTiO3 substrates having a dielectric constant of 2×104 at 4.2 K. A Nb emitter and collector electrodes were placed on the substrates, with Si or SiO2 barriers between the emitter and substrate. Base leads were made with silver paste on the back of the SrTiO3 wafers. Devices both with and without barrier layers between the collector and substrate showed transistor action at 4.2 K. Essentially no current was required to control the collector current, which ranges from a few microamperes to a few milliamperes. For devices with a 30‐μm‐diam circular emitter having a minimum emitter‐collector spacing of 15 μm, the voltage gain was 2.5–4 and the maximum transconductance 1.4 mS.
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85.30.Tv Field effect devices
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)

Anisotropy in photoluminescence and absorption spectra of fractional layer superlattices

Makoto Kasu, Hiroaki Ando, Hisao Saito, and Takashi Fukui

Appl. Phys. Lett. 59, 301 (1991); http://dx.doi.org/10.1063/1.105577 (3 pages) | Cited 14 times

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Polarization‐dependent photoluminescence (PL) and optical absorption spectra of (AlAs)1/2(GaAs)1/2 and (Al0.5Ga0.5As)1/2(GaAs)1/2 fractional layer superlattices (FLSs) were measured at room temperature. For the first time, it was observed that the spectra are dependent on their polarizations. The anisotropies in the PL and absorption spectra show that quantum confinement unambiguously occurs in the direction parallel to the surface, i.e., lateral quantum carrier confinement effect appears. This finding proves that FLSs are promising for novel optical devices.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors

Electroluminescence in the visible range during anodic oxidation of porous silicon films

A. Halimaoui, C. Oules, G. Bomchil, A. Bsiesy, F. Gaspard, R. Herino, M. Ligeon, and F. Muller

Appl. Phys. Lett. 59, 304 (1991); http://dx.doi.org/10.1063/1.105578 (3 pages) | Cited 249 times

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Porous silicon/silicon structures under anodic oxidation conditions give rise to an electroluminescence phenomenon in the visible range. Using an optical multichannel analyzer the spectral distribution of the emitted light was measured−in situ−during the anodic oxidation step. Recorded spectra show a maximum which shifts continuously from red‐orange at the beginning of the process towards the yellow range. The visible emission well above the band gap of bulk silicon is attributed to a quantum size effect in the very small size (5–20 Å) silicon island which constitutes the porous silicon skeleton. The light emission is interrupted when the current flow stops due to the formation of a continuous oxide layer at the porous silicon/silicon interface.
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78.60.Fi Electroluminescence
78.47.-p Spectroscopy of solid state dynamics
85.60.Gz Photodetectors (including infrared and CCD detectors)
81.65.-b Surface treatments

Observation of an overshoot in the capture transient of the DX center in N‐Al0.32Ga0.68As

Zhiguo Wang, T. Miller, F. Williamson, and M. I. Nathan

Appl. Phys. Lett. 59, 307 (1991); http://dx.doi.org/10.1063/1.105579 (3 pages) | Cited 2 times

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We have measured the deep level transient spectroscopy signal height of two DX levels usually observed in n‐type doped Al0.32Ga0.68As as a function of the filling pulse width. We report an overshoot in the capture transient of the DX level having a larger capture rate. We solve the rate equations for the capture processes of these two DX levels simultaneously. The capture transients thus obtained fit the experimental capture transients of these two DX levels reasonably well.
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71.55.Eq III-V semiconductors

Room‐temperature photopumped blue lasing in ZnSe‐ZnS0.06Se0.94 double heterostructures

Gang Sun, Khalid Shahzad, James M. Gaines, and Jacob B. Khurgin

Appl. Phys. Lett. 59, 310 (1991); http://dx.doi.org/10.1063/1.105580 (2 pages) | Cited 23 times

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We present results on room‐temperature photopumped lasing action in the blue region (∼4650 Å) of the spectrum for double heterostructures with ZnSe active layers. The confining layers are ZnS0.06Se0.94, providing lattice match to the GaAs substrate. The room‐temperature lasing, observed under pulsed excitation, yields threshold pump intensity as low as 58 kW cm−2 for an active layer thickness of 1500 Å.
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42.55.Px Semiconductor lasers; laser diodes
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
78.55.Et II-VI semiconductors

Meyer–Neldel rule in the space‐charge‐limited conduction of hydrogenated amorphous silicon

G. Oversluizen, K. J. B. M. Nieuwesteeg, and J. Boogaard

Appl. Phys. Lett. 59, 312 (1991); http://dx.doi.org/10.1063/1.105581 (3 pages) | Cited 2 times

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The conductivity of a hydrogenated amorphous silicon n+‐intrinsic‐n+ (n‐i‐n) structure is reported as a function of temperature. The space‐charge‐limited conductivity σ is shown to follow the Meyer–Neldel rule (MNR) [W. Meyer and H. Neldel, Z. Tech. Phys. 18, 588 (1937)]: σ =σ00 exp(Ea/kT0) exp(−Ea/kT), where Ea is the conductivity activation energy, k is Boltzmann’s constant, and T is the absolute temperature. The characteristic MNR parameters found are σ00=10−2.4±0.1(Ω cm)−1 and T0=590±10 K. These values are practically equal to those previously found for the MNR in the ohmic conductivity in a series of hydrogenated amorphous silicon n‐i‐n structures with varying i‐layer thicknesses. It is argued that the MNR can be quantitatively explained by the statistical shift of the Fermi energy and that a single set of parameters corresponding to σ00 =10−3±1(Ω  cm)−1 and T0=550±100 K is applicable for both the space‐charge limited and the ohmic conductivity of i‐type hydrogenated amorphous silicon. The MNR parameters are rather insensitive to density of states details.  
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72.80.Ng Disordered solids
72.20.Dp General theory, scattering mechanisms
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.10.Bg General formulation of transport theory

Energy‐dependent electron wave coupling between two asymmetric quantum well waveguides

Rui Q. Yang and J. M. Xu

Appl. Phys. Lett. 59, 315 (1991); http://dx.doi.org/10.1063/1.105582 (3 pages) | Cited 10 times

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We present an analysis of the electron wave directional coupling in two parallel asymmetric quantum well waveguides. By taking into account the effective mass difference between the wells we show that the transfer coefficient depends on the energy of the incident electron wave. A realistic configuration as an example of these kinds of electron wave couplers is examined. Its possible operation as an electron filter is suggested.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.40.Gk Tunneling
03.50.De Classical electromagnetism, Maxwell equations
41.20.Jb Electromagnetic wave propagation; radiowave propagation

Ideal electronic properties of a p‐Ge/p‐Al0.85Ga0.15As interface

R. Venkatasubramanian, M. L. Timmons, and J. A. Hutchby

Appl. Phys. Lett. 59, 318 (1991); http://dx.doi.org/10.1063/1.106378 (3 pages)

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The isotype p+‐Ge/p‐Al0.85Ga0.15As interface is examined in this study. It is shown that a lattice‐matched epitaxial layer of p‐Al0.85Ga0.15 on p+‐Ge acts like a minority‐carrier mirror. Evidence for this action comes from improved short‐wavelength response of a p+‐n Ge solar cell and from a tenfold reduction in the dark saturation current of a p+‐n Ge junction. At the same time, the p+‐Ge/p‐Al0.85Ga0.15As interface is electrically transparent to majority‐carrier hole transport. Similarity of measured specific resistivities of Ti/Au ohmic contacts directly to Ge and through a p‐Al0.85Ga0.15As layer to p+ Ge leads to this conclusion in spite of about 1 eV valence‐band offset at the Ge‐Al0.85Ga0.15As heterojunction interface. A possible mechanism for the hole transport through such an interface is discussed.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
72.80.Ey III-V and II-VI semiconductors
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
85.60.Dw Photodiodes; phototransistors; photoresistors

Dynamics of photoreflectance from undoped GaAs

H. Shen, M. Dutta, R. Lux, W. Buchwald, L. Fotiadis, and R. N. Sacks

Appl. Phys. Lett. 59, 321 (1991); http://dx.doi.org/10.1063/1.105583 (3 pages) | Cited 29 times

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We have studied the time constants involved in photoreflectance from several GaAs surface‐intrinsic‐n+ structures. The rise and fall times were determined from digital oscilloscope traces. We find that they depend on the intensity and wavelength of the pump and probe beams. The observed photoreflectance feature does not always follow a single exponential decay. The dependence of rise and fall times on intensity and wavelength of pump and probe beams can be accounted for by a theory based on majority‐carrier flow. The characteristic time obtained can be used to determine the potential barrier height.
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07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
07.60.Rd Visible and ultraviolet spectrometers
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties

Effects of step motion on ordering in GaInP

G. S. Chen and G. B. Stringfellow

Appl. Phys. Lett. 59, 324 (1991); http://dx.doi.org/10.1063/1.105584 (3 pages) | Cited 41 times

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Ga0.5In0.5P is observed to form the CuPt ordered structure during organometallic vapor phase epitaxy (OMVPE). Of the four possible {111} planes on which CuPt ordering could occur, only two are observed for growth on (001)‐oriented substrates, giving the (111) and (111) variants. The mechanism by which ordering occurs is not completely understood. Recent total energy calculations indicate that the phenomenon can be explained on the basis of thermodynamic considerations. Indirect evidence indicates that kinetic factors, including processes occurring at steps propagating across the surface in the two‐dimensional growth mode, affect ordering. In this letter, Ga0.5In0.5P layers have been grown on (001)GaAs substrates by OMVPE. In order to examine the effects of surface kinetic factors, the substrates were first patterned with [110] oriented grooves 5 μm wide and from 0.2 to 1 μm deep. This yields adjacent areas of epitaxial material within the grooves produced by growth via the motion of steps in opposite directions. Transmission electron diffraction reveals that the two directions of step motion produce two different variants. For exactly (001) oriented substrates, one half of the groove is filled with a single domain of the (111) variant while the other half is also a single domain, but of the (111) variant. For substrates misoriented by 6° to give [110] steps, the domains are asymmetric. The domains are very large, several square microns in cross section extending along the entire length of the groove. The strong intensities of the order‐induced spots indicate a high degree of order in the material grown in the grooves. These results demonstrate directly, for the first time, that kinetic factors related to the motion of steps on the surface determine the ordered structure formed. They also demonstrate the possibility of producing very large domains of ordered material.
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68.55.-a Thin film structure and morphology
81.15.Kk Vapor phase epitaxy; growth from vapor phase
68.35.B- Structure of clean surfaces (and surface reconstruction)
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