摘要:

We analyze the current density‐voltage characteristics of double‐barrier tunneling diodes, with different spacer layers, within the framework of a Poisson solver together with a coherent tunneling approximation for transmission probabilities. We show that varying the spacer layer thickness, together with barrier heights, changes dramatically the current density‐voltage characteristics line shape, which is revealed to be an important qualitative signature of the tunneling paths involved in the double‐barrier diodes under operation. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114289

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Buried Si1−xGexlayers grown on Si at elevated temperatures of 700 to 800 °C generally exhibit x‐ray rocking curves which are significantly broader than those predicted for perfect crystals, suggesting that the layers are strain‐relieved. However, calculations using these rocking curves show the materials to be either nearly‐ or fully‐strained. The source of x‐ray broadening accompanied by high strain is found to be an abrupt, thermally‐induced fragmentation of the layer into small, slightly misoriented regions during the cool‐down, such that the as‐grown strain remains unchanged. The fragments are typically rectangles a few micrometers wide, with well‐defined boundaries along [110]‐type directions.

ISSN:0003-6951    

DOI:10.1063/1.114290

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The mechanism of Auger recombination in type‐II heterostructures is studied theoretically. It is shown that the Auger recombination rate is a power function of temperature rather than an exponential function as in bulk materials. The feasibility of suppression of the Auger recombination process in the type‐II heterostructures is demonstrated. The possibility of controlling the Auger recombination rate is shown to be very important for development of optoelectronic devices with improved characteristics. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114291

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Recently, we proposed a three‐terminal laser structure for fast gain‐switching application using carrier heating, where hot electrons with well‐defined and variable energy are injected into an active region via resonant tunneling. A picosecond pulse generation from this device has now been analyzed, including associated transport phenomena and structure design. By means of numerical modeling we demonstrate that a resonant‐tunneling injection hot electron laser is capable of generating well‐shaped optical pulses switched by varying the injected electron energy. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114292

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Yb3+‐related photoluminescence is observed at room temperature from Yb‐doped porous silicon layers prepared by the electro‐chemical method developed by our group for Er doping of porous silicon layers. After rapid thermal annealing in a pure argon atmosphere at high temperatures (above ∼ 900 °C), samples show a sharp photoluminescence band at around 1.0 &mgr;m which is assigned to the intrashell 4f‐4ftransitions2F5/2→2F7/2of Yb3+. The enlarged energy bandgap of silicon as a result of anodization makes possible the excitation of Yb3+4f‐electrons with the recombination energy of photocarriers generated in the host porous silicon layers. ©1995 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.114293

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report the growth and characterization of crystalline, single‐phase zinc blende MnS (i.e., &bgr;‐MnS). The material was grown on ZnSe buffer layers on (100) GaAs substrates, using solid‐source molecular beam epitaxy and a novel valved S cracker with deposition at low (∼110 °C) substrate temperatures. Characterization by reflection high energy electron diffraction, high resolution transmission electron microscopy, and low temperature photoluminescence confirms the pseudomorphic nature of the growth. Beyond a certain critical thickness, the layers either become amorphous or convert into the equilibrium rock salt polymorph (&agr;‐MnS), depending on the growth temperature. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114294

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The electrical properties of nitrided silicon dioxide formed by reactive sputtering in Ar/O2/N2plasma from the SiO2target have been studied. The nitrogen mixing ratio was varied from 0% to 15%, with the argon mixing ratio kept at 80%. It is found that as more nitrogen is incorporated, the leakage current increases for electron injection from both aluminum and silicon. By nitrogen reactive sputtering, the interface states generation during constant current stress is greatly reduced in comparison with oxide sputtered in only an Ar/O2gas mixture. A mixture ratio of Ar/O2/N2equal to 80:15:5 is found to give optimum oxide quality with good resistance to interface states generation and low leakage current. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114295

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The longitudinal optic vibrational mode associated with the asymmetric stretch of the bridging oxygen atom has been studied in amorphous SiO2grown by plasma assisted oxidation of Si. In films ≤70 nm thick the mode is observed displaced by −6 cm−1with respect to the bulk value (1256 cm−1). Deconvolution of the spectra combined with chemical etchback of the films shows that they are inhomogeneous, the peak shift increasing to −12 cm−1near the Si/SiO2interface in films thicker than ∼20 nm. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114296

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Both the hexagonal and cubic GaN phases were synthesized in GaAs (001) by 50 keV N ion implantation at 380 °C and subsequent furnace annealing at 850–950 °C for 10 min–2 h. For a fluence of 1.5×1017cm−2, transmission electron microscopy revealed that cubic GaN epitaxially crystallizes as precipitates in the GaAs matrix. A cubic‐to‐hexagonal GaN phase transition was observed for extended thermal anneals. By increasing the N fluence to 3×1017cm−2, a continuous buried layer of randomly oriented hexagonal‐GaN nanocrystals was produced. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114297

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Free‐standing powder of zinc sulphide quantum particles has been synthesized using a chemical route. X‐ray diffraction analysis shows that the diameter of the particles is ∼21±2 A˚ which is smaller than the Bohr exciton diameter for zinc sulphide. UV absorption shows an excitonic peak centered at ∼300 nm corresponding to an energy gap of 4.1±0.1 eV. These particles show a luminescence band at ∼424 nm. The quantum particles could be doped with copper during synthesis without altering the UV absorption or x‐ray diffraction pattern. However, doping shifted the luminescence to 480 nm, green wavelength in the visible region. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114298

出版商:AIP    

年代:1995

数据来源: AIP