摘要:

The GaAs‐insulator interface is characterized by deep level transient spectroscopy (DLTS) and isothermal capacitance transient spectroscopy (ICTS). It is demonstrated that while DLTS can only detect transients with temperature‐dependent emission rates, ICTS can detect temperature‐independent phenomena as well. The GaAs‐insulator interface is characterized by two electron traps, with activation energies 0.67 and 0.23 eV, respectively, and a tunneling component that is detected only by ICTS. This tunneling component, which dominates the ICTS spectrum at 80 K<T< 180 K and is characterized by a field‐induced barrier reduction given by &Dgr;EE=1.4×10−3q&sqrt;E, is attributed to pure tunneling.

ISSN:0003-6951    

DOI:10.1063/1.104952

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The photoconductivity and the minority‐carrier diffusion length of CuGaSe2were studied in the photocarrier grating configuration. In order to shed some light on the carrier recombination processes, both He‐Ne and Ar‐laser illuminations were used and the light was applied either to the substrate surface or to the free surface of the films. The substantial variation of the photoelectronic properties along the film growth axis, and their dependence on the light wavelength, are interpreted in terms of the polycrystalline nature of the films. It is suggested that by properly combining deposition conditions and composition one can get a significant improvement in the phototransport properties of these materials.

ISSN:0003-6951    

DOI:10.1063/1.104953

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Using Raman spectroscopy we have investigated the spacing of the electron subbands in nominally &dgr;‐doped GaAs structures which show a considerable spread of the silicon dopant atoms along the growth direction. For optical excitation in resonance with theE0+&Dgr;0band gap, spin‐density intersubband excitations are observed. For excitation in resonance with theE1band gap we find a strong enhancement of scattering by collective intersubband plasmon‐phonon modes. The measured energy spacings between the electron subbands deviate significantly from what is expected for ideal &dgr; doping. Self‐consistent electronic subband calculations taking into account the spread of the dopant atoms along the growth direction, in contrast, yield a good quantitative agreement between calculated and measured subband spacings. This demonstrates the potential of intersubband Raman spectroscopy for the analysis of the spatial localization of dopant atoms in &dgr;‐doped structures.

ISSN:0003-6951    

DOI:10.1063/1.104954

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have carried out a direct measurement of the macroscopic volume change of GaP and GaAs induced by irradiation with an electron pulse by means of the photoelastic technique. We find that metastable states lasting over 1 ms in both GaAs and GaP are formed and that their yield increases as the temperature increases.

ISSN:0003-6951    

DOI:10.1063/1.104955

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

An analysis of the sensitivity of apnplateral magnetotransistor (LMT) fabricated in bipolar technology is presented. In addition, the role of then+‐buried layer is studied. The devices were designed as differential LMTs. It has been found that the change in sensitivity ofpnpLMT increases by one order of magnitude if then+‐buried layer is not omitted. The obtained sensitivity is the highest ever reported for apnpLMT.

ISSN:0003-6951    

DOI:10.1063/1.104956

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A type of shadow mask growth technique (cantilever shadow masking) for reduced area molecular beam epitaxial growth has been developed and applied to the growth of GaAs and InxGa1−xAs on selective areas of Si and GaAs substrates, respectively. This technique eliminates detrimental sidewall growth interactions, results in precisely positioned growth areas, and can be more readily planarized than other reduced area growth structures. This technique is particularly useful for defect density reduction during latticed‐mismatched heteroepitaxy using reduced growth areas.

ISSN:0003-6951    

DOI:10.1063/1.104957

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Admittance measurements have been made under forward bias on two types of Al/n‐GaAs contacts. The Al andn‐GaAs layers have been prepared by molecular beam epitaxy on ann+‐GaAs wafer. In the first type, which shows ideal current‐voltage characteristics, only an inductive effect was observed and no effect attributable to interface states was detected. In the second type, differing only in then‐GaAs surface which was prepared under inferior vacuum conditions, nonideality of current‐voltage characteristics and excess capacitances were both seen. The back contact being the same in both types of samples, the onset of excess capacitances must be related to the change in surface characteristics. A model which assumes a U‐shaped density of extrinsic interface states accounts simultaneously for the behavior of conductance, capacitance, and ideality factor as functions of temperature, voltage, and frequency.

ISSN:0003-6951    

DOI:10.1063/1.104958

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Following gain saturation by a short pulse, the gain recovery process in multiple quantum well optical amplifiers includes contributions from carriers occupying states with energies above the depleted states within the well, from carriers stored in the barrier layers, which serve as carrier reservoirs, and from conventional Auger recombination. Gain recovery caused by carriers from the reservoirs is rapid (7 ps) and can be made to dominate the slower (Auger) recovery process.

ISSN:0003-6951    

DOI:10.1063/1.105237

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Interactions of silicon atoms on a Ru(001) surface have been studied by synchrotron radiation photoemission spectroscopy and low‐energy electron diffraction. A stable RuxSi1−xphase with high chemical uniformity was obtained by post‐annealing the sample at 1370 °C. Upon interaction with silicon, the Rudband was significantly narrowed (by about 1 eV), and shifted towards the Fermi level. The distributions of Si 3s,3pand Ru 4din the occupied valence bands were clearly identified by using different photon energies. The chemical nature of Si‐Ru interaction is discussed.

ISSN:0003-6951    

DOI:10.1063/1.104959

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Very high C incorporation (≳1020cm−3) in GaAs was achieved by atmospheric pressure metalorganic vapor phase epitaxy (AP‐MOVPE) using CCl4as a dopant gas. Hole densities up top=1.2×1020cm−3(at least three times higher than previously reported by MOVPE) were obtained at a growth temperature of 600 °C and a V/III ratio of 2.8. The highest atomic C concentration was 1.5×1020cm−3. The hole mobilities were ∼50% larger than previously reported. CCl4was found to suppress the formation of gallium droplets and whisker growth which normally occur under low‐temperature, low V/III ratio growth conditions, allowing the growth of thin (<1 &mgr;m) heavily doped layers with mirror‐like surface morphologies. Layers withp∼1×1020cm−3showed a lattice contraction with &Dgr;a/a=−9.3×10−4. Photoluminescence studies indicate a significant band‐gap shrinkage at high doping levels.

ISSN:0003-6951    

DOI:10.1063/1.104960

出版商:AIP    

年代:1991

数据来源: AIP