摘要:

We have investigated and optimized the deposition conditions for growth of amorphous silicon (a‐Si:H) and silicon‐germanium (a‐SiGe:H) alloys at high rates using microwave glow discharge. The optimum substrate temperature is found to be higher and deposition pressure lower than the case for materials deposited at low rates using radio‐frequency glow discharge. Using the optimized conditions, we report an active‐area efficiency of 11.44% for a double‐junction, dual‐gapa‐Si:H alloy solar cell in which the bottom cell incorporatesa‐SiGe:H alloy deposited at 100 A˚/s. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114024

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

This letter investigates the effect of the substrate bias on the capture kinetics of random telegraph signals in submicron siliconp‐channel metal–oxide–semiconductor transistors. A strong dependence of the capture time constant &tgr;con the transverse electric field is observed. As a result, &tgr;c∼exp(−Ap) is observed experimentally, which is much stronger than the 1/pdependence predicted by simple Shockley–Read–Hall theory, wherebypis the surface density of free holes. The observations are explained tentatively by considering a field‐dependent hole capture cross section. The latter may result from quantization effects induced by the transverse field in the two‐dimensional inversion layer. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114025

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Using infrared absorption spectroscopy, we investigate the thermal diffusion behavior of Al atoms from monatomic Al layers embedded in a GaAs epitaxial film. After thermal annealing, the absorption peak of the two‐dimensionally localized vibrational modes at 358 cm−1due to Al layers decreases, while the peak at 362 cm−1due to isolated Al atoms increases. The 362 cm−1peak height is compared with the fraction of isolated Al atoms calculated, assuming the second nearest neighbor hopping diffusion from a monatomic Al layer into GaAs matrix. We thus determine the diffusion coefficient of Al atoms in GaAs to be 2×10−19cm2/s at 700 °C. The present study offers a simple and reliable method to investigate the impurity diffusion in crystals. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114026

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have studied the surface morphology and growth mechanism of metalorganic vapor phase epitaxy grown strained‐layer InxGa1−xAs (x=0.2 or 0.5) on GaAs with atomic force microscopy. Morphological instability of monolayer steps was observed on a 10 nm thick strained‐layer In0.2Ga0.8As. Three‐dimensional (3D) growth was observed forx=0.5 when grown at 650 °C. By lowering the growth temperature to 600 °C, the growth mode is 2‐D for 5 nm films (x=0.5). Monolayer steps and 2D islands can be seen. Increasing the layer thickness to 7.5 nm at 600 °C caused the growth of 3D islands and the generation of misfit dislocations. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114027

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have designed and studied a new type of strained semiconductor quantum well structure,variable‐strainquantumwell. The strain within the quantum well is graded from compressive to tensile in order to obtain mutually opposing slopes for the heavy‐ and light‐hole band edges, causing the heavy and light holes to experience opposite fields created by the same strain. A unique bias controlled crossover with a simultaneous red and blue quantum confined Stark shift for the heavy‐ and light‐hole transitions, respectively, has been observed by electroreflectance spectra. This results in a bias controlled change of the polarization properties and the transition energies suitable for polarization controllable photonic devices. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114028

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Frequency analysis of reflection high‐energy electron diffraction (RHEED) intensity oscillations during GaAs growth by molecular beam epitaxy on nominally‐oriented (111)B substrates is reported. Double frequency oscillations have been observed and analyzed in a wide range of substrate temperatures. Because the growth rate deduced from RHEED frequency analysis was found to be independent of substrate temperature, no Ga loss from the sample surface seems to take place during growth under conditions which allow RHEED intensity oscillations. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114029

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report on the transport properties of a silicon single‐electron transistor at 4.2 K. A quantum dot is formed in the inversion layer of a silicon metal‐oxide‐semiconductor field‐effect transistor with a dual‐gate structure by introducing controllable tunnel barriers in the narrow channel. Periodic current oscillations due to the single‐electron charging effect have been observed. Furthermore, current in the Coulomb blackade regime is explained by the inelastic cotunneling theory at finite temperatures. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114030

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A series of boron‐doped polycrystalline diamond films grown by direct current and microwave plasma deposition was studied with Raman and infrared (IR) absorption spectroscopy. A Fano line shape is observed in the Raman spectra for films with a boron concentration in a narrow range near 1021cm−3. The appearance of the Fano line shape is correlated with the disappearance of discrete electronic transitions of the boron acceptor observed in the IR spectrum and the shift of the broadened peak to lower energy. The Fano interaction is attributed to a quantum mechanical interference between the Raman phonon (0.165 eV) and transitions from the broadened impurity band to continuum states composed of excited acceptor and valence band states. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114031

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Low‐temperature (1.8 K) photoluminescence spectra of a Ga0.52In0.48P–(Al0.58Ga0.42)0.52In0.48P multiple quantum well have been measured as a function of hydrostatic pressure from 0 to 5.0 GPa. The extrapolation to zero pressure of the energy of the indirectk‐and‐real‐space barrierXto well &Ggr; transition allows the direct determination of the valence band offset for this heterojunction system. A value of &Dgr;Ev=(0.35±0.05)&Dgr;Egis found, in good agreement with values previously determined from the theoretical modeling of quantum well transition energies. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114032

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The photovoltage shows a very complicated behavior and could be considered as a new approach to the investigation of the excess carrier transfer in semi‐insulating (SI) semiconductors. Both time‐resolved short‐circuit (SC) photovoltage and photocurrent at the same energies in the range 1.13–1.49 eV for SI GaAs were measured. The peculiarities of the photovoltage were explained in terms of hole transfer between EL2 deep center and a series of acceptor levels. The influence of the electrons and holes was distinguished, which is known to be impossible via conventional photocurrent measurements. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114033

出版商:AIP    

年代:1995

数据来源: AIP