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27 Jan 1992

Volume 60, Issue 4, pp. 401-517

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Experimental determination of the influence of gain saturation on the temperature dependence of threshold current in short AlGaAs‐GaAs quantum‐well lasers

H. Jung, E. Schlosser, and R. Deufel

Appl. Phys. Lett. 60, 401 (1992); http://dx.doi.org/10.1063/1.106670 (3 pages) | Cited 4 times

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In GaAs‐AlGaAs single and multiple quantum‐well (SQW and MQW) ridge lasers, grown by molecular beam epitaxy, the temperature dependence of the threshold current, expressed by the characteristic temperature T0, is investigated as a function of the cavity length (L) at temperatures between 20 °C and 93 °C. SQW lasers, in contrast to MQWs, show at room temperature a strong decrease in T0 from 250 K to about 100 K when the length is reduced from 400 to 200 μm. We found that by further reducing L to about 130 μm, a strong increase in T0 up to 250 K occurs and T0 decreases again to 80 K for 60 μm SQW lasers. This T0 behavior in SQW lasers is directly correlated to the gain saturation of the n=1 transition and the switch of the laser emission to the n=2 transition. In MQW lasers, T0 is constant at all cavity lengths, even at high temperatures, indicating that no gain saturation occurs.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

All‐optical reflectivity tuning and logic gating in a GaAs/AlAs periodic layered structure

M. Cada, J. He, B. Acklin, M. Proctor, D. Martin, F. Morier‐Genoud, M.‐A. Dupertuis, and J. M. Glinski

Appl. Phys. Lett. 60, 404 (1992); http://dx.doi.org/10.1063/1.106671 (3 pages) | Cited 24 times

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The optical nonlinearity of a GaAs/AlAs periodic layered structure was experimentally investigated for the first time. The shift of the reflectivity peak with increasing intensity was observed. A reflectivity contrast of about 10:1 was obtained by varying the incident intensity. Hysteresis loops due to the response delay of both the electronic and the thermal nonlinearity were observed. All‐optical logic operations were also demonstrated. A further improvement of the structure may lead to a new type of optical bistable device.
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78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
42.65.Pc Optical bistability, multistability, and switching, including local field effects

Strain induced optical waveguides in lithium niobate, lithium tantalate, and barium titanate

O. Eknoyan, H. F. Taylor, Z. Tang, V. P. Swenson, and J. M. Marx

Appl. Phys. Lett. 60, 407 (1992); http://dx.doi.org/10.1063/1.106672 (3 pages) | Cited 18 times

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Channel waveguides have been produced in LiNbO3, LiTaO3, and BaTiO3 ferroelectric crystals by depositing thick SiO2 films at an elevated temperature and patterning them by reactive ion etching. The static strain resulting from the large thermal expansion mismatch between the substrate and film causes a localized increase in the refractive index via the strain‐optic effect. In addition, an electro‐optic contribution to the index increase is believed to result from a surface charge distribution which compensates the electric field due to the piezoelectric effect. Single‐mode waveguides at a wavelength of 0.633 μm for both polarizations have been produced in x‐cut LiNbO3, with losses of 0.8 dB/cm for TE polarization and 0.9 dB/cm for TM polarization. The 11‐μm‐wide channel waveguides were formed by a z‐axis strain induced by a 2.8‐μm‐thick SiO2 film deposited at 300 °C. Electro‐optic modulation was also demonstrated in these waveguides. Guiding for both polarizations was also observed in LiTaO3 and BaTiO3 channel waveguides at 0.83 μm wavelength.
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42.79.Gn Optical waveguides and couplers
65.40.De Thermal expansion; thermomechanical effects
78.20.Jq Electro-optical effects
77.70.+a Pyroelectric and electrocaloric effects

Demonstration of an x‐ray ring‐aperture microscope for inertial‐confinement fusion experiments

D. Ress, R. A. Lerche, and L. Da Silva

Appl. Phys. Lett. 60, 410 (1992); http://dx.doi.org/10.1063/1.106673 (3 pages) | Cited 13 times

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We are investigating the use of annular (ring) apertures to image high‐energy x‐ray emission (≳4 keV) from inertial‐confinement fusion targets. In our scheme, a coded image is formed on a detector (such as x‐ray film) by x rays that pass through a narrow annulus cut in a sheet of high‐Z material such as gold. Signal‐to‐noise ratio calculations show a factor of 10 advantage of ring‐aperture imaging over conventional pinhole imaging. Simultaneous pinhole and ring‐aperture images of small (≊20 μm diam), laser‐driven, x‐ray sources were obtained in recent experiments. We used a 10‐μm‐wide, 1‐mm‐diam annulus in a 6‐μm thickness of gold; a 10‐μm‐diam pinhole was in the center of the annulus. Unfolds of the coded images have signal‐to‐noise ratios a factor of 20 larger than the pinhole images. The ring‐aperture microscope is a promising new technique to image inertial‐confinement fusion targets and other compact sources of high‐energy x rays.
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52.70.La X-ray and γ-ray measurements
07.85.-m X- and γ-ray instruments
42.30.Va Image forming and processing

Effects of compressive and tensile uniaxial stress on the operation of AlGaAs/GaAs quantum‐well lasers

Sandip Tiwari, Richard S. Bates, Christoph S. Harder, and A. Behfar‐Rad

Appl. Phys. Lett. 60, 413 (1992); http://dx.doi.org/10.1063/1.106640 (3 pages) | Cited 3 times

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The consequences of strain on the threshold current, relaxation oscillation frequency, and wavelength of operation of lasers have been investigated using an external uniaxial stress impressed on Ga1−xAlxAs/GaAs ridge‐guide quantum‐well lasers employing graded index and separate confinement. Under the conditions of small strain (≤0.1%), the threshold current increases monotonically from compressive to tensile conditions by as much as 30%, the relaxation oscillation frequency decreases monotonically from compressive to tensile conditions by as much as 100% when operating close to threshold conditions, and the mode spectrum shifts in accord with the shifts expected in the subband energy levels. These observations indicate that changes in effective mass, and hence in transparency and differential gain, are the dominant causes of this variation. For smaller band‐gap structures, such as Ga1−xInxAs1−yPy lasers, where carrier lifetime effects should be expected to dominate, we speculate that the threshold current density may show a decrease for both compressive and tensile strain.
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42.55.Px Semiconductor lasers; laser diodes
62.50.-p High-pressure effects in solids and liquids

Role of substrate temperature in molecular‐beam epitaxial growth of high‐power GaAs/AlGaAs lasers

S. V. Iyer, H. P. Meier, Shlomo Ovadia, C. Parks, D. J. Arent, and W. Walter

Appl. Phys. Lett. 60, 416 (1992); http://dx.doi.org/10.1063/1.106620 (3 pages) | Cited 6 times

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The growth of high‐quality GaAs/AlGaAs graded‐index separate‐confinement heterostructure single‐quantum‐well diode lasers is shown to be critically dependent on growth temperature. The temperature‐dependent nature of oxygen incorporation in the cladding and active regions and its effect on laser performance is investigated in detail. A model is presented that takes the incorporation, desorption, and accumulation of impurities in different regimes into account.  
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42.55.Px Semiconductor lasers; laser diodes
68.55.-a Thin film structure and morphology
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties

Gallium arsenide: A new material to accomplish passively mode‐locked Nd:YAG laser

Zhuhong Zhang, Liejia Qian, Dianyuan Fan, and Ximing Deng

Appl. Phys. Lett. 60, 419 (1992); http://dx.doi.org/10.1063/1.106621 (3 pages) | Cited 21 times

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A passively mode‐locked Nd:YAG laser using a semi‐insulating GaAs is accomplished. Ultrashort pulses, shorter than 10 ps, with an energy of 10 μJ per pulse are obtained. The dynamics of the pulse formation is described.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.Fc Modulation, tuning, and mode locking

High contrast ratio self‐electro‐optic effect devices based on inverted InGaAs/GaAs asymmetric Fabry–Perot modulator

Li Chen, Kezhong Hu, R. M. Kapre, and A. Madhukar

Appl. Phys. Lett. 60, 422 (1992); http://dx.doi.org/10.1063/1.106622 (3 pages) | Cited 3 times

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We demonstrate a new class of ‘‘normally off’’ high contrast ratio asymmetric Fabry–Perot (ASFP) reflection modulators based on a blue‐shift of the Fabry–Perot mode under bias. The negative differential resistance (NDR) exhibited by the photocurrent‐bias behavior was exploited to implement self‐electro‐optic devices (SEED) using as the load (a) a photodiode (D‐SEED), and (b) a phototransistor (T‐SEED). In the D‐SEED scheme, a contrast ratio of ∼50:1 with ∼20% throughput was realized. The T‐SEED configuration was found to offer nearly as high contrast ratio but with a ∼200:1 gain from the control light beam. Moreover, the ASFP modulators used belong to the inverted configuration which offers considerable convenience in device integration and optical interconnections.
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42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.79.Sz Optical communication systems, multiplexers, and demultiplexers
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors

Plasma soft x‐ray source generated by 4‐ns excimer laser pulses

A. L. Morsell, M. Powers, and H. Shields

Appl. Phys. Lett. 60, 425 (1992); http://dx.doi.org/10.1063/1.106623 (3 pages) | Cited 3 times

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A XeCl excimer laser system is described which generates short‐duration (4 ns) pulses of up to 980 mJ in energy. Pulses of 800 mJ have been focused to an intensity of ∼2×1012 W cm−2 on an iron target to produce soft x rays. Measurements of x rays in the 0.8–1.4‐keV range have demonstrated 44 mJ energy per pulse into 2π sr, and a pulse width of 5.3 ns (FWHM). The estimated laser to x‐ray energy conversion efficiency was ∼5.5%.
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42.55.Lt Gas lasers including excimer and metal-vapor lasers
07.85.-m X- and γ-ray instruments
41.50.+h X-ray beams and x-ray optics

Interface traps and interface recombination in AlGaAs/GaAs quantum well laser diodes

K. Xie, C. R. Wie, J. A. Varriano, and G. W. Wicks

Appl. Phys. Lett. 60, 428 (1992); http://dx.doi.org/10.1063/1.106624 (3 pages) | Cited 4 times

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The current‐voltage characteristics and deep traps of various GaAs/AlGaAs graded‐index separate confinement heterostructure quantum well laser diode structures are studied as a function of the growth temperature and threshold current. It is shown that the interface nonradiative recombination processes cause a high threshold current. An impurity‐related deep level with activation energy Ea=0.48 eV at the interface region and an interface state with wide energy distribution were found in the high threshold current diodes. The current‐voltage characteristics show that interface recombination, rather than bulk recombination, is the dominant carrier transport process in the diodes and is responsible for the high threshold current.
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42.55.Px Semiconductor lasers; laser diodes
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

4×4 nonblocking integrated acousto‐optic space switch

C. S. Tsai and P. Le

Appl. Phys. Lett. 60, 431 (1992); http://dx.doi.org/10.1063/1.106625 (3 pages) | Cited 8 times

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A 4×4 nonblocking integrated acousto‐optic space switch has been realized, for the first time, in a Y‐cut LiNbO3 channel‐planar‐channel composite waveguide 0.1×1.0×3.0 cm3 in size. Measured performances for nonblocking switching at the optical wavelength of 0.6328 μm include a worst‐case crosstalk of −15.6 dB, an average throughput of −16.0 dB, a frequency resolution (frequency increment required for switching between adjacent output ports) of 18.0 MHz, and a reconfiguration time of 0.145 μs.
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42.79.Sz Optical communication systems, multiplexers, and demultiplexers
42.81.Wg Other fiber-optical devices
42.82.Bq Design and performance testing of integrated-optical systems

Low‐temperature preparation of SiO2/Si(100) interfaces using a two‐step remote plasma‐assisted oxidation‐deposition process

T. Yasuda, Y. Ma, S. Habermehl, and G. Lucovsky

Appl. Phys. Lett. 60, 434 (1992); http://dx.doi.org/10.1063/1.106626 (3 pages) | Cited 63 times

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SiO2/Si(100) interfaces have been prepared by a low‐temperature, 200–300 °C, remote plasma‐assisted oxidation‐deposition process. The oxidation: (i) creates ∼0.5 nm of SiO2; (ii) removes residual C from an otherwise H‐terminated Si surface; and (iii) produces a SiO2/Si interface with a midgap trap density of ∼1×1010 cm−2 eV−1, and when combined with remote plasma‐enhanced chemical vapor deposition (RPECVD) of SiO2, (iv) forms a SiO2/Si structure with properties comparable to those prepared by thermal oxidation of Si at 850–1050 °C.
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85.40.Hp Lithography, masks and pattern transfer
85.30.Tv Field effect devices
81.65.-b Surface treatments
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)

Microstructure of the emitter polycrystalline silicon/silicon interface in bipolar transistors after rapid thermal annealing

Y. Kim, T. M. Liu, K. F. Lee, D. Y. Jeon, J. A. Rentschler, and A. Ourmazd

Appl. Phys. Lett. 60, 437 (1992); http://dx.doi.org/10.1063/1.107462 (2 pages) | Cited 1 time

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We use high‐resolution transmission electron microscopy to determine the microstructure of the emitter polycrystalline (poly) Si/Si interface of real bipolar transistor devices after rapid thermal annealing. Our results quantify the size and density of interfacial oxide voids (pinholes), the areal fraction of the interface covered with voids, and the amount of epitaxial regrowth after annealing in the range 1000–1150 °C. Correlation of these results with the characteristics of the devices shows that the most dramatic electrical changes occur before 2% of the poly‐Si/Si interfacial area is covered with oxide voids.
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85.30.Pq Bipolar transistors
68.35.Dv Composition, segregation; defects and impurities

Absence of electrical activity at high‐angle grain boundaries in zone‐melt‐recrystallized silicon‐on‐insulator films

P. V. Evans, D. A. Smith, and C. V. Thompson

Appl. Phys. Lett. 60, 439 (1992); http://dx.doi.org/10.1063/1.106627 (3 pages) | Cited 1 time

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Zone‐melt recrystallization (ZMR) of polycrystalline silicon‐on‐insulator films has been used to produce a variety of tilt grain boundaries for electrical characterization. Electron channeling patterns reveal the grains to have misorientations up to ∼25° and the parallel boundaries to be separated by distances of up to ∼1 mm. Current‐voltage measurements indicate that the boundaries are electrically inactive, with no evidence of defect gap states even after long high‐temperature anneals.
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73.61.Cw Elemental semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors
61.72.Mm Grain and twin boundaries

Selective Si epitaxial growth by plasma‐enhanced chemical vapor deposition at very low temperature

K. Baert, P. Deschepper, J. Poortmans, J. Nijs, and R. Mertens

Appl. Phys. Lett. 60, 442 (1992); http://dx.doi.org/10.1063/1.106628 (3 pages) | Cited 9 times

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A rf‐plasma chemical vapor deposition process for selective epitaxial Si growth from SiH4 and SiF4 at a deposition temperature of 300–400 °C is described. Selective epitaxial growth is obtained as a balance of deposition precursors versus etching by F species. Also, the results indicate that a high H‐surface coverage is not essential to deposit crystalline Si films by very low temperature rf‐plasma chemical vapor deposition. P‐doped films with a mobility of 80 cm2/V s and a carrier concentration of 3×1018 cm−3 are reported.
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85.40.Hp Lithography, masks and pattern transfer
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Electrical characteristics of oxynitrides grown on textured single‐crystal silicon

Ming‐yin Hao and Jack C. Lee

Appl. Phys. Lett. 60, 445 (1992); http://dx.doi.org/10.1063/1.106629 (3 pages) | Cited 16 times

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The electrical characteristics of oxynitrides grown on textured single‐crystal silicon are discussed in this letter. This study compares the I‐V, C‐V, charge trapping, interface state generation, and breakdown characteristics of this new gate dielectric with those of oxides and oxynitrides grown on untextured silicon, and oxides grown on textured silicon. Textured oxynitrides were found to have enhanced conduction and significantly reduced interface state generation. Furthermore, they exhibit an improved immunity to charge trapping under high‐field stress, and a significantly higher charge‐to‐breakdown QBD compared to the textured oxides. These properties make the textured oxynitride a promising gate dielectric for applications in electrical‐erasable programmable read‐only memories (EEPROMs).
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85.30.Tv Field effect devices
77.55.-g Dielectric thin films
73.61.Ng Insulators
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)

Photoemission spectroscopy of GaAs:As photodiodes

D. T. McInturff, J. M. Woodall, A. C. Warren, N. Braslau, G. D. Pettit, P. D. Kirchner, and M. R. Melloch

Appl. Phys. Lett. 60, 448 (1992); http://dx.doi.org/10.1063/1.106630 (3 pages) | Cited 29 times

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We report on photoemission measurements of molecular‐beam‐epitaxy‐grown GaAs p‐i‐n structures, in which the optically active insulating GaAs layer contains As precipitates (GaAs:As). GaAs:As is formed by low‐temperature growth of GaAs at 225 °C, followed by an anneal at 600 °C. Layers grown in this way have been reported to be sensitive to subband‐gap light. The measured barrier height of 0.7 eV, extracted from a well‐behaved Fowler plot, indicates that the mechanism for photodetection involves arsenic clusters embedded in GaAs acting as internal Schottky barriers.
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85.60.Dw Photodiodes; phototransistors; photoresistors
73.40.Ty Semiconductor-insulator-semiconductor structures
73.30.+y Surface double layers, Schottky barriers, and work functions
72.40.+w Photoconduction and photovoltaic effects

Improved crystalline quality of Si1−xGex formed by low‐temperature germanium ion implantation

Ken‐ichi Shoji, Akira Fukami, Takahiro Nagano, Takashi Tokuyama, and Cary Y. Yang

Appl. Phys. Lett. 60, 451 (1992); http://dx.doi.org/10.1063/1.106631 (3 pages) | Cited 20 times

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Improvement of crystalline quality in Si1−xGex formed by germanium ion implantation has been found. End‐of‐range defects were drastically reduced in number by lowering the substrate temperature during implantation with doses on the order of 1016 cm−2. This improvement was confirmed by electrical characterization of p‐n junctions formed in the SiGe layer as well as by transmission electron microscopy.  
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
61.72.uf Ge and Si
61.80.Jh Ion radiation effects
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Heavy arsenic doping of silicon grown by atmospheric‐pressure chemical vapor deposition at low temperatures

P. D. Agnello, T. O. Sedgwick, M. S. Goorsky, and J. Cotte

Appl. Phys. Lett. 60, 454 (1992); http://dx.doi.org/10.1063/1.106632 (3 pages) | Cited 7 times

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Arsenic doping of epitaxial grown Si over the temperature range from 850 °C to 550 °C was investigated in an ultraclean atmospheric‐pressure chemical vapor deposition reactor. Growth was carried out from dichlorosilane (DCS) in H2 carrier gas. Arsenic could be incorporated into single crystal silicon at levels approaching 10 at. %. Carrier concentrations exceeding 1×1020/cm3 were obtained for the as‐grown films. The material remained single‐crystalline, as measured by ion channeling and cross‐section transmission electron microscopy, and exhibited excellent surface morphology with no Hillock formation observed. AsH3 dramatically enhanced the growth rate of Si at lower temperatures.
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85.40.Hp Lithography, masks and pattern transfer
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
61.72.uf Ge and Si
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Coexistence of Wannier–Stark localization and negative differential velocity in superlattices

A. Sibille, J. F. Palmier, and F. Mollot

Appl. Phys. Lett. 60, 457 (1992); http://dx.doi.org/10.1063/1.106633 (3 pages) | Cited 26 times

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We show the coexistence of Wannier–Stark localization as monitored by photoconduction experiments, and of negative differential velocity (NDV) for electrons in a perpendicularly biased GaAs/AlAs superlattice. The critical electric field for the onset of NDV, and that for the appearance of localization as monitored optically are nearly the same, which exemplifies the fundamental link between Wannier–Stark quantization [Phys. Rev. 117, 432 (1960)], and Esaki–Tsu nonlinear transport [IBM J. Res. Dev. 14, 61 (1970)].
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71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
72.20.Ht High-field and nonlinear effects
73.40.Gk Tunneling

Vertical scaling in heterojunction bipolar transistors with nonequilibrium base transport

A. F. J. Levi, B. Jalali, R. N. Nottenburg, and A. Y. Cho

Appl. Phys. Lett. 60, 460 (1992); http://dx.doi.org/10.1063/1.106634 (3 pages) | Cited 13 times

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We experimentally measure a departure from conventional scaling of current gain β with base thickness xB in abrupt junction n‐p‐n heterojunction bipolar transistors. It is empirically established that extreme nonequilibrium electron transport in the base causes β to vary as approximately 1/xB. In our AlInAs/InGaAs transistors this new behavior occurs for base thickness xB≲1000 Å.
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85.30.Pq Bipolar transistors
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
72.20.Ht High-field and nonlinear effects
72.80.Ey III-V and II-VI semiconductors

Blue/green pn junction electroluminescence from ZnSe‐based multiple quantum‐well structures

W. Xie, D. C. Grillo, R. L. Gunshor, M. Kobayashi, G. C. Hua, N. Otsuka, H. Jeon, J. Ding, and A. V. Nurmikko

Appl. Phys. Lett. 60, 463 (1992); http://dx.doi.org/10.1063/1.106635 (3 pages) | Cited 37 times

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The successful p doping of ZnSe by substitutional nitrogen using a plasma cell incorporated into the molecular beam epitaxy chamber has led to the development of electroluminescent devices based on carrier injection at a pn junction. The light emitting diode structures described here are grown on a GaAs substrate using a tetragonally distorted (In,Ga)As buffer layer to provide lattice matching between the substrate and the active II–VI region. The result of the incorporation of the buffer layer is an essentially dislocation‐free active region. The letter discusses optical properties as well as the x‐ray and transmission electron microscopy characterization of the quantum well device structures.
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85.60.Jb Light-emitting devices
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
78.60.Fi Electroluminescence

Elimination of heterojunction band discontinuities by modulation doping

E. F. Schubert, L. W. Tu, G. J. Zydzik, R. F. Kopf, A. Benvenuti, and M. R. Pinto

Appl. Phys. Lett. 60, 466 (1992); http://dx.doi.org/10.1063/1.106636 (3 pages) | Cited 22 times

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Conduction‐ or valence‐band discontinuities occurring at the junction of two heterogeneous semiconductors can be eliminated by appropriate doping of the interfacial region. We show by analytic and self‐consistent calculations that simultaneous modulation doping and parabolic compositional grading result in flat band‐edge potentials. The new concept is applied to distributed Bragg reflectors for vertical cavity lasers. The structures grown by molecular‐beam epitaxy exhibit significantly lower resistances as compared to step‐graded distributed Bragg reflectors.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
61.72.U- Doping and impurity implantation
42.55.Px Semiconductor lasers; laser diodes

Principle differences between the transport properties of normal AlGaAs/InGaAs/GaAs and inverted GaAs/InGaAs/AlGaAs modulation doped heterostructures

T. Schweizer, K. Köhler, and P. Ganser

Appl. Phys. Lett. 60, 469 (1992); http://dx.doi.org/10.1063/1.106637 (3 pages) | Cited 11 times

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The electrical properties of Al0.3Ga0.7As/InxGa1−xAs modulation doped heterostructures grown on GaAs substrates were studied. We found for the normal and inverted heterostructures principal differences of the transport properties. For an InAs mole fraction of 0.2 the inverted modulation doped heterostructures show a stronger decrease in the electron mobility of the two‐dimensional electron gas if the critical layer thickness of the In0.2Ga0.8As layer is exceeded, in comparison to the normal heterostructures. This behavior can be explained by the relaxation process of the In0.2Ga0.8As layer. For InxGa1−xAs heterostructures with x≳0.3 the growth mode changes from two‐dimensional to three‐dimensional growth, which leads to interface roughness, degrading the transport properties of the normal heterostructure. Thus for high InAs mole fractions the inverted heterostructures show better transport properties in comparison to the normal heterostructures.
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68.55.-a Thin film structure and morphology
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Stable cw operation at room temperature of a 1.5‐μm wavelength multiple quantum well laser on a Si substrate

M. Sugo, H. Mori, Y. Sakai, and Y. Itoh

Appl. Phys. Lett. 60, 472 (1992); http://dx.doi.org/10.1063/1.106638 (2 pages) | Cited 27 times

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Room‐temperature cw operation of an InGaAs/InGaAsP multiple quantum well (MQW) laser diode on a Si substrate is reported. The MQW laser emits at a 1.54 μm wavelength and exhibits no degradation after over 2000 h of operation. Employing a hybrid organometallic vapor phase epitaxy/vapor mixing epitaxy method and a layer structure for improving crystalline quality, high‐quality MQW layers are obtained. A stable longitudinal mode spectrum demonstrates the effectiveness of the MQW active layer.
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42.55.Px Semiconductor lasers; laser diodes
85.40.Hp Lithography, masks and pattern transfer
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