摘要:

Temperature dependent photoluminescence decay measurements have been used to study the minority carrier dynamics in iodine‐doped ZnSe grown by molecular beam epitaxy. The existence of three deep acceptor levels with energies at 80, 120, and 350 meV above the valence band has been established. The 80 and 120 meV levels have a density dependence directly related to the iodine doping density whilst the level at 350 meV does not. Significant broadband donor–acceptor emission is observed from this material and appears to be associated with the acceptor level at 350 meV. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115493

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

It has been shown that a pressurized water boiling (PWB) at 2 atmospheric pressures and 120 °C in an autoclave vessel accelerates significantly hydrogenation and neutralization of B acceptors in Si. Compared with boiling at atmospheric pressure, PWB reduces more the free‐hole IR absorption and increases more the sheet resistivity in B implantedp+layer onn‐type substrate. An IR absorption of B–H stretching vibration (∼1907 cm−1) has been detected at 16 K for ap+layer which was PWB processed for only 6 h. Concentration increase of H‐related species in water and faster diffusion of H in Si at higher temperature may be the cause. In contrast with other hydrogenation techniques, water boiling hardly passivates donors in Si even for 10 h PWB. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115494

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The valance band structure of metalorganic vapor phase epitaxy (MOVPE) grown strained GaxIn1−xAs/InP single quantum well structures is experimentally verified by the determination of the effective in‐plane hole masses. The masses are obtained by performing magnetotransport experiments. Mobilities up to 8700 cm2/V s for gallium content ofx=0.3 were reached. The effective heavy hole masses of compressively strained GaInAs are drastically reduced compared to bulk material in excellent agreement to calculations using thek⋅p‐perturbation theory, whereas the masses of the uppermost valence band of tensile strained material appear to be rather high. Consequently, no experimental determination was possible in the latter case. A precise analysis of the Shubnikov–de Haas oscillation patterns of compressively strained quantum wells shows a spin splitting of the uppermost heavy hole band, containing two different effective masses. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115509

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report the luminescence characteristics of Sr(S,Se):Ce,Cl thin film electroluminescent devices, fabricated by co‐evaporation of SrS:Ce,Cl pellet and elemental Se. From the electroluminescence spectra measurements for varied S:Se mole ratio and temperature, it is found that the relative intensity of green emission band to blue emission band decreases with increasing lattice constant of the host lattice. This can be qualitatively accounted for as being caused by a nonradiative energy transfer from the emission band of Ce3+to the absorption band due to defects associated with anion vacancies in the host lattice. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115510

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Data are presented on curved‐resonator AlGaAs–GaAs quantum well heterostructure laser diodes employing a deep‐oxide guiding structure formed by a combination of impurity‐induced layer disordering and native oxidation. Room‐temperature, continuous wave (cw) threshold currents as low as ∼13 mA are measured for a ∼5 &mgr;m wide, 100 &mgr;m radius half‐ring laser employing a deep‐oxide structure. For similar 150 &mgr;m radius devices, cw threshold currents as low as ∼19 mA are observed (∼7 &mgr;m width), with total output powers exceeding 30 mW. Spectral data indicate single‐mode operation over a large current range (25–100 mA). The low‐threshold characteristics are attributed to the excellent current and optical confinement of the deep‐oxide structure, combined with low edge scattering loss. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115511

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The hydrogenated amorphous silicon (a‐Si:H) thin film transistors (TFTs) with silicon nitride as a gate insulator have been stressed with negative and positive bias to realize the instability mechanisms. It is found that the threshold voltages of thea‐Si:H TFTs are positively shifted under low negative bias stress and then negatively shifted for large negative gate bias. The positive threshold voltage shift is ascribed to the increased states in the band gap near the conduction band by the negative gate bias. As the negative bias continuously increases, the hole trapping in the silicon nitride or at thea‐Si:H/silicon nitride interface will become dominant, resulting in the negative threshold voltage shift. A similar turnaround phenomenon is also observed with respect to the stress time. On the other hand, for the TFTs stressed with positive gate bias, the monotonic increase of the threshold voltage shift with stress time is attributed to the state creation. Nevertheless, the distributions of the created states in the energy band gap for thea‐SiH TFTs after the stress will be affected by the bias polarity based on the defect pool model, reflecting the asymmetrical subthreshold swing change against the positive and negative stress bias. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115512

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Using a femtosecond pulsed laser, ultrafast electrical pulses were optoelectronically generated on silicon and indium phosphide by edge illumination of a coplanar transmission line. Backing up theory with experiment, we demonstrate that this pulse‐generation method is material independent, thus providing a powerful tool for broadband characterization of devices made on a wide range of semiconductor substrates. We also demonstrate that edge illumination enables the generation of 550 fs electrical pulses on indium phosphide and 800 fs pulses on silicon—the fastest pulses to date on bulk silicon. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115513

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have found a new photoluminescence (PL) band with a maximum at 0.9 eV and a halfwidth of 0.1 eV at 4.2 K in polycrystalline Si thin films deposited on glass at 625 °C. The PL band strongly shifts toward low energy with increasing the temperature (1.3 meV/K) and toward high energy with increasing the excitation intensity. Hydrogenation of polycrystalline Si enhances the PL intensity by factor of 3 to 5. The luminescence characteristics are consistent with radiative recombination of electrons and holes trapped in tail states of the conduction and the valence band, respectively. Excellent agreement is achieved between the 0.9 eV band shape and theoretical calculations based on a band‐tail recombination. It is also argued that a corresponding luminescence spectroscopy provides a new possibility for band‐tail diagnostics in polycrystalline Si thin films. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115515

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Molecular beam epitaxy of Si1−xGexalloys, using gaseous Si2H6and solid Ge as sources, has been studied over the entire composition range (0≤x≤1). From the measured growth rates as a function ofx, it is clear that the presence of Ge tends to decrease the Si incorporation rate. This establishes growth via adatom migration to kink sites in a dissociative chemisorption process. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115516

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A highly efficient lateral transport mechanism has been observed in stable defect layers (SDL) inp‐type silicon. The SDLs were produced by proton implantation followed by rapid thermal anneal. Photogenerated carriers have been collected at a Schottky junction several millimeters away from the generation site. This transport distance is more than 30 times the diffusion length in comparable bulk material. A model is proposed in which bending of the energy bands near the SDL expels majority carriers, leaving no substantial recombination mechanism for minority carriers trapped in the layer. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115517

出版商:AIP    

年代:1995

数据来源: AIP