摘要:

Photoluminescence measurements have been made on GaAs samples stressed with piezoelectric bimorphs. We show that measurable shifts in the energy gap can be obtained by mechanically stressing the semiconductor with a piezoelectric transducer. This principle can be applied to fabricate a class of wavelength‐tunable electro‐optic devices, such as tunable semiconductor lasers, light‐emitting diodes, and photodetectors.

ISSN:0003-6951    

DOI:10.1063/1.105644

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have investigated infrared absorption properties at normal incidence inp‐type Ga1−xInxAs/Al1−yInyAs strained quantum wells. They are designed such that the ground state for holes is a light‐hole state, which results from the effects of biaxial tensile strain in the quantum wells. We find that in this light‐ and heavy‐hole inverted structure the infrared absorption from intervalence subband transitions can be greatly enhanced up to 8500 cm−1, which is comparable to that in the intrinsic Hg1−xCdxTe detector. This novel structure’s ability to detect infrared radiation at normal incidence makes it promising for infrared photodetection applications.

ISSN:0003-6951    

DOI:10.1063/1.105645

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

CeO2layers epitaxially grown on (100) silicon substrates by electron‐beam evaporation were investigated and proved to have (110) orientation. X‐ray diffraction measurements showed the CeO2layers consist of more than 98% volume fraction of the (110) component. Cross‐sectional high‐resolution transmission electron microscopy and selected‐area electron diffraction clearly verified the above configuration of crystallographic orientations and that the ⟨100⟩ direction in the CeO2(110) plane is parallel with the ⟨110⟩ direction in the Si(100) plane. The cross‐sectional lattice image clarified the existence of a ∼60‐A˚‐thick intermediate amorphous layer between the CeO2layer and the silicon substrate. Moreover, the high density of defects such as dislocations and low‐angle boundaries that exist in the vicinity of the interface agree well with Rutherford backscattering and channeling measurements.

ISSN:0003-6951    

DOI:10.1063/1.105646

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Energy relaxation processes for minority electrons inp‐GaAs are investigated by time‐resolved photoluminescence (PL) measurements using an up‐conversion technique with a high time resolution of 130 fs. By measuring the time evolution of PL intensity, the energy relaxation time of electrons is obtained directly. Moreover, electron distribution created by laser excitation which is in a thermally nonequilibrium state is successfully observed. With increasing hole concentration, the time response in PL intensity becomes fast. This implies that electron‐hole interaction plays a key role in energy relaxation in high hole concentration. By detailed analyses of PL intensity, it can be found that the relaxation time by electron‐hole interaction is approximately 500 fs or less, and electrons which are in a nonequilibrium state just after excitation are thermalized rapidly within about 200 fs at the first stage by electron‐hole interaction.

ISSN:0003-6951    

DOI:10.1063/1.105647

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Inverted modulation doped structures typically exhibit degraded electrical characteristics. For the AlInAs‐GaInAs heterojunction system, the reduction in electron mobility for two‐dimensional electron gases formed at inverted interfaces can be greater than 50% at 300 K as compared to those formed at normal interfaces. Our data show that the reduction in mobility is due to the movement of Si into the GaInAs channel. The Si movement is found to be dramatically reduced by growing the AlInAs spacer at the inverted interface at a substrate temperature of 300–350 °C. Device structures have been grown using this technique which exhibit the highest conductivity obtained for any 2DEG system.

ISSN:0003-6951    

DOI:10.1063/1.106394

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

GaAs/AlGaAs heterojunction bipolar transitors (HBTs) utilizing highly Be‐doped base layers display a rapid degradation of dc current gain and junction ideality factors during bias application at elevated temperature. For example, the gain of a 2×10 &mgr;m2device with a 4×1019cm−3Be‐doped base layer operated at 200 °C with a collector current of 2.5×104A cm−2falls from 16 to 1.5 within 2 h. Both the base emitter and base collector junction ideality factors also rise rapidly during device operation, and this current‐induced degradation is consistent with recombination‐enhanced diffusion of Be interstitials producing graded junctions. By sharp contrast, devices with highly C‐doped (p=7×1019cm−3) base layers operated under the same conditions show no measurable degradation over much longer periods (12 h). This high degree of stability is most likely a result of the fact that C occupies the As sublattice, rather than the Ga sublattice as in the case of Be, and also has a higher solubility than Be. The effect of nearby implant isolated regions in promoting Be diffusion is also reported.

ISSN:0003-6951    

DOI:10.1063/1.105623

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Raman scattering has been combined withinsitusputtering for a depth resolved Raman spectroscopic characterization of semiconductor structures. Using optical excitation in resonance with higher lying band gaps, such as theE1band gap of GaAs, a depth resolution of a few nm can be achieved along with an enhanced sensitivity due to resonance effects in the scattering efficiency. The present experimental technique is demonstrated by recording a composition profile from a GaAs/AlxGa1−xAs multiple quantum well structure. Furthermore, the ability of lattice site selective depth profiling of dopant distributions is shown for Si incorporated on Ga and As lattice sites, respectively, in Si+implanted and annealed GaAs.

ISSN:0003-6951    

DOI:10.1063/1.105624

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Laser diode action in the blue‐green has been observed from (Zn,Cd)Se quantum wells within ZnSe/Zn(S,Se)p‐nheterojunctions up to 250 K. Operation is reported for two different configurations for which the GaAs substrate serves either as then‐ orp‐type injecting contact. In pulsed operation, output powers exceeding 0.6 W have been measured in devices prepared on bothn‐type andp‐type GaAs epitaxial buffer layers and substrates.

ISSN:0003-6951    

DOI:10.1063/1.105625

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have observed Wannier–Stark localization in extremely shallow superlattices (SL) at 77 K, which results in a quasi‐blue shift of the absorption edge at very small electric fields. The formation of a Stark ladder is also clearly shown. The blue shift results in a change in absorption coefficient from 1.7 &mgr;m−1(at 0.2 V/&mgr;m) to 0.98 &mgr;m−1(at 0.6 V/&mgr;m) for a GaAs/Al0.07Ga0.93As SL; for a GaAs/Al0.02Ga0.98As SL we obtain a change from 2.1 &mgr;m−1(at 1.1 V/&mgr;m) to 0.9 &mgr;m−1(at 1.5 V/&mgr;m).

ISSN:0003-6951    

DOI:10.1063/1.105626

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We present the results of a systematic study of the dependence of intersubband infrared detector performance on the subband energies. By using samples cut from different positions on a single wafer grown with a known thickness variation it is possible to obtain a set of devices for which the well width varies in a controlled manner, but the barrier height remains fixed. Current versus voltage and responsivity measurements demonstrate the importance of the detector performance on the exact location of the upper state: optimum peak response is obtained when the subband is resonant with the top of barrier.

ISSN:0003-6951    

DOI:10.1063/1.106379

出版商:AIP    

年代:1991

数据来源: AIP