摘要:

We report the studies of luminescence intensity and lifetime dependences on temperature for Nd‐doped GaP and GaAs samples grown by metalorganic chemical vapor deposition. It is found that, with above band‐gap excitation, the temperature dependence of GaP:Nd reveals a two‐step decreasing behavior as the sample temperature increases. This phenomenon is due to the fact that there exist two kinds of Nd centers (type I and type II) in GaP. Although type I Nd centers produce strong luminescence at low temperatures, their intensities drop rapidly above 40 K. On the other hand, type II Nd centers show a near constant intensity up to 150 K and can still be observed up to room temperature. We also found, for a given Nd center, that the luminescence lifetime dependence on temperature is identical to the temperature quenching behavior of luminescence intensity. From the similarity between the quenching behaviors of Nd‐related luminescence intensities and lifetimes, we conclude that the temperature quenching of luminescence intensity of these Nd‐doped GaP and GaAs samples is mainly due to deexcitation rather than the reduction of excitation efficiency.

ISSN:0003-6951    

DOI:10.1063/1.104725

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Boron‐doped Czochralski silicon samples with [B]∼1017cm−3have been heated at various temperatures in the range 800–1300 °C in an atmosphere of hydrogen and then quenched. The concentration of [H‐B] pairs was measured by infrared localized vibrational mode spectroscopy. It was concluded that the solubility of atomic hydrogen is greater than [Hs] = 5.6 × 1018 exp( − 0.95 eV/kT)cm−3at the temperatures investigated.

ISSN:0003-6951    

DOI:10.1063/1.104726

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Minority electron lifetimes in molecular beam epitaxy grown Be‐dopedp‐type GaAs are characterized systematically. Samples grown at temperatures from 550 to 700 °C have hole concentrations from 1017to 1020cm−3. Although electron lifetime in samples grown at temperatures higher than 650 °C remains nearly constant for each free‐carrier concentration, it decreases significantly at lower growth temperatures. These tendencies are observed in common for various hole concentrations. These results can be explained in terms of an increase in nonradiative recombination centers incorporated during growth.

ISSN:0003-6951    

DOI:10.1063/1.104727

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The influence of substrate orientation on Be transport during GaAs molecular beam epitaxy is studied by secondary‐ion mass spectrometry. Substrates are misoriented from (100) toward (111)A, and the epitaxial growth is performed at 630 °C for Be doping at (5–7)×1019cm−3. Surface segregation and anomalous diffusion similarly depend on substrate orientation. With (311)Aorientation, the Be transport is dramatically reduced from its value with conventional (100) orientation. These results are qualitatively explained by considering the effect of atomic steps on the growing surface.

ISSN:0003-6951    

DOI:10.1063/1.104728

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The sidewall damage in a silicon substrate caused by trench etching has been investigated using deep level transient spectroscopy. In order to detect surface and near‐surface modifications resulting from trench etching, a special device structure consisting of ann+/pjunction array is used. It is found that three kinds of deep level are introduced onto the sidewall. The energy levels of these traps areEc− 0.30 eV,Ev+ 0.60 eV, andEv+ 0.66 eV, respectively. The deep level atEv+ 0.60 eV acts as aG‐Rcenter. The reverse current characteristics of the same device have three modes with activation energies of 0.59, 0.64, and 0.13 eV, respectively. These modes also result from the sidewall damage. It is found that a transformation of the sidewall damage occurs at 1000 °C. TheG‐Rcenter and two of the reverse current modes disappear, but the damage is not completely annealed out because the others still remain.

ISSN:0003-6951    

DOI:10.1063/1.104729

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have studied the low‐field magnetoresistance of the two‐dimensional electron gas in GaAs/<m1;&33>AlxGa1−xAs in the presence of a two‐dimensional lateral surface superlattice (2D LSSL) potential, and observed, for the first time, the guiding‐center drift resonance, previously reported for one‐dimensional LSSL structures. The 2D LSSL potential is created by applying a voltageVgto a 200 nm period grid‐gate structure fabricated on top of the sample and can be tuned continuously from being repulsive to attractive by tuningVg.

ISSN:0003-6951    

DOI:10.1063/1.104730

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have investigated the gas pressure dependence of electron cyclotron resonance (ECR) plasma‐enhanced chemical vapor deposition (PECVD) and preparedn‐type &mgr;c‐SiC:H with wide optical band gap (2.1–2.5 eV) and high dark conductivity (10−3– 1 S/cm). It has been suggested from plasma diagnoses of the ECR plasma that at low gas pressure a strong etching effect of hydrogen radicals and/or ions dominates the film growth process and the hydrogen ions impinging on the growing surface make the formation of &mgr;c‐SiC:H difficult, and that at high gas pressure, for the formation of &mgr;c‐SiC:H, there are nonemissive radicals contributing to the surface coverage or a nucleus formation mechanism which has not been taken into consideration in conventional rf‐PECVD.

ISSN:0003-6951    

DOI:10.1063/1.104731

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Roll‐off of the current gain cut‐off frequency inNpNdouble‐heterojunction bipolar transistors for large collector currents has been analyzed. The analysis includes such effects as the electron barrier formed at the collector base junction due to electron accumulation. Included in this investigation is also lateral electron diffusion before injection into the collector space‐charge region at the base‐collector heterointerface once the barrier is formed. The available data obtained in SiGe heterojunction bipolar transistors are in good agreement with this model.

ISSN:0003-6951    

DOI:10.1063/1.104732

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

InAsxP1−x/InP strained multiple quantum wells with strain as high as 2.5% were grown by gas‐source molecular beam epitaxy. Successful control of the arsenic composition over a wide range was achieved by two different growth techniques. Structural and optical studies, such as high‐resolution x‐ray rocking curve, cross‐sectional transmission electron microscopy, photoluminescence, and absorption measurement, indicate that we have obtained high quality multiple quantum wells that are suitable for optoelectronic applications.

ISSN:0003-6951    

DOI:10.1063/1.104733

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The double‐heterostructure optoelectronic switch is demonstrated as a three‐terminal laser. The basic laser structure employs a graded index single quantum well (GRIN SQW) and implements the third‐terminal injector as a self‐aligned implant to the inversion channel. The implant simultaneously serves as the optical confining layer. Threshold currents of 500 A/cm2are obtained and complete control of the switching characteristic is obtained with an input current density of 0.8 A/cm2.

ISSN:0003-6951    

DOI:10.1063/1.104707

出版商:AIP    

年代:1991

数据来源: AIP