摘要:

We report the use ofinsitureflectance spectroscopy for real‐time monitoring of the metalorganic vapor phase epitaxy (MOVPE) growth of InGaAsP films.Insituoptical measurements have not been previously reported for this materials system because of its strong absorption in the spectral range of commonly available detectors (&lgr;<1100 nm). To acquire reflectance data beyond the absorption regions of these films we used a grating spectrometer with a Si/PbS dual detector having a wavelength range of 400–2500 nm. Measurements were made during growth of InP/InGaAs/InP double heterostructures and 1.3 &mgr;m InGaAsP MQW laser device structures. The multiwavelength reflectance data enabled extraction of the film optical constants, determination of deposition rates to better than 1%, and provided nanometer scale thickness sensitivity for MQW samples. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116946

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We show that the transient intersubband photocurrent in a GaAs/AlGaAs quantum‐well infrared photodetector (QWIP) consists of two dynamical components, which are associated, respectively, with the drift motion of photoexcited carriers and with the extra injection current induced by the generated nonequilibrium space charges. The decay time &tgr; of the latter component depends critically on the temperature of the sample and the applied bias voltage. For a temperature ofT=22 K, decay times in excess of 15 &mgr;s are found. A simple model of the refilling process of the space charges is presented, showing, that the slow component corresponds approximately to the dielectric relaxation time of the structure along the growth direction. While the slow component in the present 8‐period structure corresponds to about 50% of the total photocurrent, it is negligible in standard QWIP structures containing 40 or more periods, where ⩾99% of the intersubband photocurrent proceeds on a picosecond time scale. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116947

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We study the effects of gate dopant species (boron, arsenic, or phosphorous) concentration (1×1019cm−3–1×1021cm−3) and microstructure (as‐deposited amorphous or polycrystalline silicon gate) on the electrical and reliability characteristics of ultrathin oxides and N2O oxynitrides (60 A˚). In order to minimize polysilicon depletion, a high gate dopant concentration is desirable. However, for devices with BF2doped gates, it is found that because of boron penetration through the thin gate oxide, device characteristics degrade as the gate doping concentration increases, thus an intermediate gate doping must be chosen. In contrast, samples with arsenic and phosphorous doped gates show no degradation as the doping level increases. Optimization of gate microstructure for N2O and O2dielectrics is also discussed. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116948

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report Raman scattering study on InN single crystalline films with wurtzite form. The films were grown on sapphire substrates by microwave‐excited metalorganic vapor phase epitaxy and optical phonon properties of the films were investigated. BothA1(LO) andE2(2)peaks, which are related to a longitudinal optical phonon mode and a doubly degenerated mode, respectively, were observed at 596 cm−1with the full width of 36 cm−1at half maximum intensity and at 495 cm−1with the full width of 20 cm−1at half maximum intensity. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116949

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report ballistic‐electron‐emission microscopy (BEEM) imaging andspatiallyresolvedspectroscopy of InxGa1−xAs/GaAs misfit dislocations 800 A˚belowthe surface. Majority‐carrier scattering by a fraction of misfit dislocations was seen to locally reduce the BEEM current and to give logarithmic spatial dependence, which suggests charging of the dislocation cores. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116950

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Raman scattering has been used to investigate strained InAs islands grown on InP(001), in correlation with transmission electron microscopy. Symmetry arguments, selective resonance at the InAsE1‐like transition and comparison with a single‐quantum‐well structure allowed to distinguish between the islands and remaining wetting layer signals. Whereas the vibrational modes of the 2D thin layers are greatly affected by interface roughness and confinement, strain effects mainly account for the phonon frequency shifts in the islands. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116951

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Data are presented on the luminescence characteristics of GaAs layers adjacent to native‐oxide regions derived from epitaxial AlGaAs and InAlP films. The native‐oxide ‘‘window’’ layers capping the epitaxial structures are formed by the oxidation of the exposed Al0.9Ga0.1As and In0.48Al0.52P cladding layers. Extensive photoluminescence and time‐resolved photoluminescence studies performed at 300 K show that both the luminescence intensity and lifetime from GaAs ‘‘active regions’’ drop dramatically when the adjacent AlGaAs window layer is oxidized completely. However, there is a marked increase in the efficiency and decay time of the luminescence with the oxidation of InAlP window layers which are grown immediately above the GaAs layer. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116952

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

To investigate the effects of strain and quantum confinement, Auger rates are calculated for ann‐type strained InAs0.9Sb0.1/In0.87Ga0.13As mid‐infrared laser structure as a function of temperature. Compressive strain in the quantum wells reduces the mass of the holes which leads to a reduction in the Auger rate compared with an unstrained quantum well. The rate reduction is explained in terms of a qualitative analysis of the role of strain. The rate includes contributions from inter‐subband Auger transitions which are found to dominate the rate at low temperature.

ISSN:0003-6951    

DOI:10.1063/1.117091

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report an infrared comparative photoluminescence and absorption study of optical properties in quaternary GaInAsSb/AlGaAsSb strained single‐quantum‐well structures grown by molecular beam epitaxy with the indium composition of 0.25 and 0.33. The light‐hole‐related luminescence structure observed in the lower indium composition sample disappears in the sample with higher indium composition due to the larger band splitting of heavy and light holes induced by the strain. This observed transition from type I to type II states for light holes is in good agreement with our theoretical prediction that it may occur for the indium composition larger than 0.30. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117092

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Short‐period GaAs/AlGaAs quantum wire array (QWA) was fabricated by metalorganic chemical vapor deposition on the GaAs substrate with submicron gratings. A strong photoluminescence signal derived from highly dense QWA was detected in the as‐grown sample. To identify the signal more clearly, all the layers except QWR regions should be removed. However, the small dimension of the sample made it difficult to do that with conventional lithography techniques. We have developed a novel lithography technique which can be applied to nonplanar structures. We could completely remove the (100) and the (111)A quantum well (QW) layers using the technique. As a result, we could clearly observe the optical properties of short‐period QWA by improving the carrier capture efficiency of QWR regions. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117093

出版商:AIP    

年代:1996

数据来源: AIP