摘要:

We have fabricated GaSb/InAs hot‐electron transistors with base widths of 30 to 200 A˚. The barrier height of thermionic emission was evaluated with two techniques; deducing from values of collector current density itself, and from its temperature dependence. The difference between the two results reveals that electrons are emitted from both &Ggr; andLvalleys of the GaSb conduction band. From the measured barrier height, the energy of the ground quantum level formed in InAs base was also deduced. Its dependence on the base width was compared with simple calculation where nonparabolicity of the InAs conduction band was considered. It indicates electron density in the InAs base is enhanced due to electron’s transfer from GaSb to InAs.

ISSN:0003-6951    

DOI:10.1063/1.106227

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The image potential between an ion and an etched sidewall is shown to be important in the dry etching of high‐aspect ratio features. Low‐energy ions are attracted to the walls of an etched trench, resulting in wall collisions which can lead to loss of etch directionality and slow vertical etch rates. Estimates are given for the depth at which one‐half of the ion flux into an etched trench is lost to one of the etched walls, as a function of trench width and ion energy. The effect is particularly important in the etching of quarter‐micron features and smaller using ion energies less than 200 eV.

ISSN:0003-6951    

DOI:10.1063/1.106228

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Hydrogenated amorphous silicon‐carbon alloys (a‐SiC:H) with band gaps around 1.9 eV have been prepared using trisilylmethane (TSM) as the carbon source by plasma‐enhanced chemical vapor deposition. Compared toa‐SiC:H alloys prepared from the conventional CH4/SiH4mixture, the TSM‐based films show sharper optical‐absorption edge, weaker defect‐related optical absorption, lower methyl group concentration, longer ambipolar diffusion length, and higher photoconductivity.

ISSN:0003-6951    

DOI:10.1063/1.106229

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Exposure to ultraviolet light induces paramagnetic, metastable defects in hydrogenated amorphous silicon nitride (a‐SiN1.6:H) thin films. The thermally induced decay of the light‐induced paramagnetic defects follows a stretched exponential dependence on annealing time, exp [−(t/&tgr;)&bgr;], and displays a temperature‐dependent &bgr; and &tgr;. These results indicate that a multiple trapping or a trap‐controlled hopping mechanism is involved in the annealing process with an apparent activation energy of 0.43 eV.

ISSN:0003-6951    

DOI:10.1063/1.106230

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Thus far the many reports concerning the utilization of the photocarrier grating (PCG) method have assumed that ambipolar transport takes place in such a PCG when it is imposed on hydrogenated amorphous silicon (a‐Si:H). This assumption, which is decisive in the interpretation of the experimental results in terms of the ambipolar diffusion length, has not been tested thus far. In this letter a corresponding testing criterion is proposed, and it is demonstrated that whenever ambipolarity is lost, the PCG‐derived diffusion lengths may be wrong. The finding that ambipolarity is maintained in device qualitya‐Si:H is shown to confirm the theoretical suggestion that, whenever observed, the ambipolarity ina‐Si:H is due to shallow trapping effects.

ISSN:0003-6951    

DOI:10.1063/1.106231

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Resonant Raman scattering work is reported on local vibrational modes (LVM) of Si and Be in highly doped III‐V semiconductors, such as GaAs, InAs, and InSb. Raman scattering by the LVM of Si donors on group‐III lattice sites is found to be strongly enhanced for incident photon energies matching theE1band‐gap energy of the host semiconductor indicating a rather narrow resonance in the scattering cross section. Raman scattering by LVM produced by acceptors, by contrast, is observed for a much wider range of photon energies, which corresponds to a much broader resonance. Possible explanations for this difference in resonance behavior are discussed including resonant donor energy levels derived from theL‐point conduction‐band minima. The present observations demonstrate, further, that attention must be paid to the appropriate choice of incident photon energies in order to achieve maximum sensitivity in a LVM Raman experiment.

ISSN:0003-6951    

DOI:10.1063/1.106232

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The oxide desorption processes of InP have been investigated under molecular‐beam epitaxy conditions, determining thickness and composition of the surface layer by x‐ray photoelectron spectroscopy and surface reconstructions by reflection high‐energy electron diffraction (RHEED). Under P2stabilization the oxide desorbs within 5 min at 490 °C and a (2×4) reconstruction is observed. On the other hand, heating in a flux of As4molecules results in the formation of an InAs layer at the top of the oxide, which strongly reduces the oxide desorption rate. The complete removal of the oxygen requires at least 520 °C and typically leaves a 1‐nm‐thick overlayer of InAs. In this case RHEED gives no indication whether the surface is oxide free.

ISSN:0003-6951    

DOI:10.1063/1.106233

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The limiting conditions are presented of selective epitaxial growth (SEG) on a SiO2‐patterned Si (001) substrate for Si gas‐source molecular‐beam epitaxy by use of 100% Si2H6. In the initial stage of growth, epitaxial Si was selectively grown on a Si surface in the wide temperature range of 500–850 °C. On the other hand, polycrystalline Si nucleation on a SiO2surface was intimately related to the total volume of supply gas. At a substrate temperature of 700 °C and a Si2H6flow rate of 60 sccm, a SEG layer could be deposited at a rate as high as 645 A˚/min.

ISSN:0003-6951    

DOI:10.1063/1.106234

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Ion‐beam synthesis of a buried &bgr;‐FeSi2layer in Si is demonstrated. In the experiments Si(111) substrates have been implanted with 450‐keV Fe+ions. Samples have been analyzed by Rutherford backscattering spectrometry, x‐ray diffraction, and transmission electron microscopy. Annealing at 900 °C of samples implanted with 6×1017Fe+/cm2causes formation of a buried layer consisting of grains with lateral dimensions of approximately 5 &mgr;m. The epitaxy of &bgr;‐FeSi2(110) and/or (101) planes parallel to the Si(111) substrate plane is observed.

ISSN:0003-6951    

DOI:10.1063/1.106235

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Using variable pressure for tuning the band structure and variable infrared light pulse intensity for tuning the number of Si‐related shallow donor metastable states, we have demonstrated that these states are effective mass‐like states linked to each of the conduction band &Ggr;,L, andXminimum. The evolution of their binding energies with their increasing density is shown to decrease and the Mott transition for the &Ggr;‐like states has been also observed.

ISSN:0003-6951    

DOI:10.1063/1.106236

出版商:AIP    

年代:1991

数据来源: AIP