摘要:

Franz–Keldysh electrorefraction and electroabsorption were measured for semi‐insulating InP and GaAs at several electric fields and several wavelengths near the absorption edge. For InP, the experimental results are described well by an effective mass approximation theory with a correction that accounts for the exponential absorption tail. It is shown that, at least in InP, Franz–Keldysh electrorefraction is under some conditions much stronger than the Pockels effect.

ISSN:0003-6951    

DOI:10.1063/1.96527

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Double heterostructures consisting of GaSb active layers with Al0.4Ga0.6Sb cladding layers were grown by molecular beam heteroepitaxy on Si substrates. The intrinsic ∼12% lattice mismatch between the GaSb and the Si at the growth temperature is largely taken up by a GaSb/AlSb superlattice. The larger thermal contraction of the GaSb layer relative to that of Si causes the GaSb layer to be under severe dilatory strain relative to the Si substrate at room temperature. Optically pumped laser emission ranging from 1.62 &mgr;m at 80 K to 1.82 &mgr;m at 350 K was observed. The threshold varied somewhat nonexponentially with temperature, with a change in slope at ∼250 K. The exponential threshold‐temperature dependences at 80 and 300 K areT0=158 and 100 K, respectively, and are higher than previously reported for GaSb lasers. At 300 K the threshold corresponds to an effective current of 12 kA/cm2.

ISSN:0003-6951    

DOI:10.1063/1.96528

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The linewidth of distributed feedback semiconductor lasers with partially reflecting facets is analyzed theoretically to study its dependence on the grating phases at the facets. For most phase combinations, the linewidth is found to be reduced compared to its value expected in the absence of grating, i.e., the value expected for a similar Fabry–Perot laser. The extent of reduction increases with the coupling coefficient &kgr;. The calculated results are in qualitative agreement with the recent observations on phase tunable distributed feedback lasers.

ISSN:0003-6951    

DOI:10.1063/1.96529

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We report a simple optical correlation technique which is capable of measuring the intrinsic response speeds of fast photosensitive electronic devices. The appeal of the method is that neither high‐speed electrical connections to a device nor cross‐correlation measurements between two devices are required. An example is given of measurements of the response speed of a GaAs Schottky barrier photodiode. Under appropriate illumination conditions the detector is found to be sufficiently fast to be capable of replacing optical second harmonic generation techniques for monitoring the quality of a beam of 1.5 ps pulses.

ISSN:0003-6951    

DOI:10.1063/1.96530

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We report the first successful growth of an epitaxial insulator‐metal‐semiconductor structure. The substrate is Si (111), on which a layer of CoSi2followed by a layer of CaF2have been grown by molecular beam epitaxy. The epitaxy of the top CaF2layer improves upon rapid thermal annealing. The epitaxial relations of the two overlayers with respect to the substrate have been determined. The lattice of the CoSi2is rotated 180° with respect to the Si lattice, while the CaF2is aligned with the Si lattice. This work demonstrates that it is possible to combine these materials in a single heteroepitaxial structure and may have important applications in three‐dimensional integration.

ISSN:0003-6951    

DOI:10.1063/1.96531

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Rapid heating with an electron beam has been used to react overlayers of rare‐earth (RE) metals with (111) Si, forming epitaxial layers of silicides of Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. Under conventional furnace annealing, forming such silicides on Si typically leads to rough, pitted surfaces. The use of fast beam heating not only results in a much smoother surface topology but also helps promote epitaxial growth on (111) Si in both solid and liquid phase reactions. These epitaxial silicides have a hexagonal RESi∼1.7structure (defected AlB2type). Their orientation with the Si substrate is (0001)∥(111), with predicted lattice mismatches ranging from +0.83 to −2.55%.

ISSN:0003-6951    

DOI:10.1063/1.96532

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Some unusual behavior in the temperature dependence of the Young’s modulus along the direction of the reinforcing graphite fibers in a graphite/aluminum composite has been observed. The decrease of the Young’s modulus with decreasing temperature as measured by ultrasonic techniques, utilizing noncontacting electromagnetic acoustic transducers, is shown to be due to the strong dependence of the fiber modulus on stress, which existed as a result of the mismatch between the coefficients of thermal expansion for the fiber and the matrix. Results appear significant in the selection of suitable combination of fibers and matrices for achieving thermally stable composites.

ISSN:0003-6951    

DOI:10.1063/1.96533

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Modification of large grainp‐CdTe by Ru is shown to reduce the sub‐band‐gap response and increase minority‐carrier diffusion length from 0.67 to 0.92 &mgr;m. Contact potential difference (CPD) measurements onn‐ andp‐CdTe show shifts in surface Fermi level in opposite directions corresponding to increase in barrier height in each case. The amphoteric nature of Ru on CdTe surfaces depending on conductivity type is thus inferred. The magnitudes of the changes in CPD are approximately equal to the increase of open circuit voltageVocobserved in photoelectro‐chemical cells.

ISSN:0003-6951    

DOI:10.1063/1.96534

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We have unpinned the Fermi level at the surface of bothn‐ andp‐type (100) GaAs in air. Light‐induced photochemistry between GaAs and water unpins the surface Fermi level by reducing the surface state density. Excitation photoluminescence spectroscopy shows a substantial decrease in both surface band bending and surface recombination velocity in treated samples, consistent with a greatly reduced surface state density (&bartil;1011cm−2). Capacitance‐voltage measurements on metal‐insulator‐semiconductor structures corroborate this reduction in surface state density and show that the band bending may be controlled externally, indicating an unpinned Fermi level at the insulator/GaAs interface. We discuss a possible unpinning mechanism.

ISSN:0003-6951    

DOI:10.1063/1.96535

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We report the observation of two negative conductance regions in the low‐temperature photocurrent‐voltage characteristic of tight‐binding multiquantum well (35 periods) 1‐&mgr;m‐thick Al0.48In0.52As/ Ga0.47In0.53As superlattices grown by molecular beam epitaxy. The two peaks occur at voltages corresponding to a potential energy drop across the superlattice period equal to the energy differences between the first two excited states and the ground state of the quantum wells. This provides direct evidence of sequential resonant tunneling between the ground and excited states of adjacent wells alternated with intrawell energy relaxation.

ISSN:0003-6951    

DOI:10.1063/1.97007

出版商:AIP    

年代:1986

数据来源: AIP