摘要:

Thickness profiles of silicon dioxide films deposited by ozone‐augmented tetraethoxysilane have been experimentally measured in ultra‐high‐aspect ratio capillaries. The deposition profiles exhibit a sharp drop in film thickness near the capillary entrance followed by a gradual decrease in thickness along the capillary. A feature‐scale model for this process has been developed which includes the effect of by‐products on the reaction kinetics and transport inside the structure. Simulated deposition profiles agree well with the experimental data, indicating that a trapped by‐product inside the capillary inhibits the film‐forming reaction, thus producing the characteristic film profile. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115222

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Reactive ion beam etching of aluminum indium antimonide, gallium indium antimonide heterostructures in electron cyclotron resonance plasma using methane/hydrogen/nitrogen/silicon tetrachloride (CH4/H2/N2/SiCl4) mixtures has been performed at room temperature. Due to the ratio of chlorine to methane, formation of an indium chloride layer on the etched surface is avoided, thus resulting, in etched surfaces as smooth as the original ones and flat mesa sidewalls. Infrared diodes (2.3&mgr;m) have been fabricated using this etching technology. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115223

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Delayed photocurrents were observed in GaAs/AlAs type‐I short‐period superlattices by measuring time‐resolved photoresponses under ultrashort optical pulse excitation. According to the envelope function calculations, theX1state in AlAs barriers resonates with the &Ggr;2state in the adjacent GaAs wells at a bias voltage where the delayed photocurrents were conspicuous. These results strongly suggest that the dynamic carrier transport process is significantly influenced byX1‐&Ggr;2resonance effects in the superlattices. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115224

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Dynamics of the neutral‐acceptor‐bound exciton transition (theI1line) in a Mg dopedp‐type GaN epitaxial layer grown by metalorganic chemical vapor deposition (MOCVD) have been studied by time‐resolved photoluminescence emission spectroscopy. Two emission lines in theI1transition region have been resolved in the time‐resolved spectra, possibly due to the existence of two energy states of the Mg impurities after postgrowth thermal annealing. The recombination lifetimes of the acceptor‐bound exciton transition have been measured under different conditions including temperature, excitation intensity, and emission energy. From these measurements, a value of about 450 ps for the radiative recombination lifetime has been obtained, which is an important physical quantity for optoelectronic device applications based on GaN. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115225

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A systematic dependence of the density and type of stacking fault defects with substrate surface chemistry and film growth mode was observed in ZnSe‐based films grown on GaAs substrates. Namely, the density of Frank‐type stacking faults is very large for films grown on Ga‐rich surfaces, but is very low for films grown on As‐stabilized surfaces exposed to Zn prior to the growth of the film. In contrast, the density of Shockley‐type stacking faults increases for films grown by 3D growth mode at the initial stages of growth, but decreases greatly if the films are grown by the layer‐by‐layer growth mode. Films with stacking fault densities as low as 104/cm2were obtained by growing the films by the layer‐by‐layer growth on GaAs epilayers with As‐stabilized surfaces that were exposed to Zn for 1–2 min prior to the growth of the films. ©1995 American Institute of Physics.[S0003‐6951(95)00548‐6]

ISSN:0003-6951    

DOI:10.1063/1.115226

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Theoretical results for the temperature dependence of the thermal expansion coefficient for 3C–SiC are reported using a phenomenological lattice dynamical theory in the quasiharmonic approximation. The linear thermal expansion coefficient &agr; of 3C–SiC exhibits a variation with temperature much like that of the specific heat and, unlike other tetrahedrally coordinated materials, it does not attain a negative value at lower temperatures. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115227

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have measured the avalanche breakdown voltage (Vb) in GaAsp‐i‐ndiodes as a function of hydrostatic pressure up to 14 kbar. The pressure coefficient ofVbwas small and opposite in sign compared to that of the band gap. A lucky‐drift calculation ofVbincluding the effects of pressure on both the phonon scattering and ionization rates showed that the ionization threshold energy does not scale with the band gap. Instead, the effective threshold scales with an average of the energies of the &Ggr;,X, andLconduction‐band minima. This is direct evidence that pair production yields final electron states distributed between conduction‐band valleys. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115228

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The luminescence from heavily doped ZnSe:N shows a deep broadband whose position was found to depend strongly on the excitation intensity and sample temperature. The peak was found to shift towards higher energies with increasing intensity, but in contrast to the standard donor–acceptor pair (DAP) model, shifted towards lower energies with increasing temperatures. This behavior is explained using a modified DAP model that takes into account the perturbations of the band and impurity states caused by fluctuations in the concentrations of the ionized impurities. This model led to an estimate of 2.52 eV for the PL peak, with a width of 140 meV, for the case of low temperature and low excitation intensity, in rough agreement with our observations. The effect of these fluctuations on film conductivity is also discussed. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115229

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We formulate on the basis of field‐dependent subband structures a design principle for the TE‐polarized electroabsorption (EA) effect in quantum wells (QWs) that includes all the possible subband‐to‐subband and excitonic absorptions. In contrast with trade‐off between band‐gap‐wavelength shift and exciton oscillator strength in enlarged well widths, the transition from the second valence subband dominantly contributes to the EA enhancement. The reason is clarified in conjunction with the nonparabolicity in the valence‐subband structures. The enhancement of the EA change through the second‐subband transition in lattice‐matched wide QWs can be exploited to build highly efficient EA modulators. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115230

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

In this letter we present a simple but effective single band model for the calculation of the current‐voltage characteristics in InAs/AlSb double barrier resonant tunneling diodes. We have obtained a very good agreement for the overall characteristics and especially for both peak and valley current densities as compared with previously published data. The influence of the doping concentration in the injection layer on the current density is studied, as well as the influence of the quantum well width. We discuss a diode design with a view to tunneling diode oscillators suitable for submillmeter wave mixing. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115231

出版商:AIP    

年代:1995

数据来源: AIP