摘要:

The effects of defect-enhanced, impurity-free, quantum-well (QW)-barrier compositional intermixing caused by the SiO2cap annealing at 750 °C of a 1.5-&mgr;m InGaAsP/InP multiple quantum-well (MQW) laser structure have been studied by photoluminescence (PL). A substantial band-gap blue shift, as much as 112 nm(∼66 meV), was found in the structure and the value of the shift can be controlled by the anneal time. The amount of the shift does not depend on the thickness of the SiO2cap layer. Ridge-waveguide lasers were fabricated on the different areas of the wafer, with and without a SiO2cap during a 60 s anneal. The lasing wavelength of the laser produced with the SiO2cap has a 78 nm blue shift over that of the laser without the SiO2cap. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118213

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We performed heating measurements on holes in a strained Ge/Si0.4Ge0.6quantum well and electrons in a strained Si/Si0.7Ge0.3quantum well in the temperature range 0.3–5.5 K. While a power law dependence of carrier temperature on current,Te∼Ia, was observed for both samples, the measured values for the current exponent are different:a=0.50±0.02 for the Ge sample and 0.40±0.02 for the Si sample. We attribute this exponent difference to the difference in their phonon dimensionality. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119190

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Ion implantation induced surface expansion (swelling) of 6H-SiC was investigated through the measurement of the step height between implanted and unimplanted areas. The samples were irradiated at room temperature with 500 keVAl+ions in the dose range1.25×1014–3×1015 ions cm−2.Swelling was related to dose and the area density of ion-induced damage measured by Rutherford backscattering channeling technique. The observed trend is consistent with the hypothesis that the volume expansion of the ion damaged crystal is proportional to the area density of displaced atoms, plus an additional relaxation occurring at the onset of the crystalline to amorphous transition. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119191

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We have fabricated an antiresonant Fabry–Perot saturable absorber (A-FPSA), for potential use in laser passive mode locking, using metalorganic vapor phase epitaxy followed by ion implantation and thermal annealing. We show that the implantation/annealing cycle shortens the free-carrier dwell time without degrading the other optical properties of the A-FPSA. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119192

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

In0.15Ga0.85N/GaNandIn0.15Ga0.85N/In0.05Ga0.95Nmulti quantum well (MQW) structures grown on (0001) sapphire substrates were investigated by high-resolution x-ray diffraction and cross-sectional transmission electron microscopy. The results show that ultrathin MQWs with fairly good crystallinity and precisely controlled clear parallel interfaces were grown. Laser diode structures with MQWs were also studied, and the results suggest that these superlattice structures retain their high quality even after being subjected to high temperatures during the subsequent growth ofp-type GaN as the optical guiding layer,p-type GaAlN as the cladding layer, andp-type GaN as the contact layer. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119193

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The fact that single-crystal Si would make an ideal material for thin-film transistor devices has long been recognized. Despite this awareness, a viable method by which such a material could be directly produced on a glass substrate has never been formulated. In this letter, it is shown experimentally that location-controlled single-crystal Si regions on aSiO2surface can be obtained in a glass-substrate compatible manner, via excimer-laser-based sequential lateral solidification of thin Si films using a beamlet shape that self-selects and extends a single grain over an arbitrarily large area. This is accomplished by controlling the locations, shape, and extent of melting induced by the incident excimer-laser pulses, in such a manner as to induce interface-contour-affected sequential super-lateral growth of crystals, during which the tendency of grain boundaries to align approximately orthogonal to the solidifying interface is systematically exploited. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119194

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A novel sensor, based on the intervalley transfer of electrons inAlxGa1−xAs (x∼0.3)subjected to hydrostatic pressure and/or strain is proposed. The operation characteristics are evaluated, optimized theoretically, and demonstrated experimentally. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119195

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Effects of an interaction between the electronic and lattice systems on the optical spectra of a wurtzite GaN epilayer were investigated. The exponentially increasing absorption tail was well explained as an Urbach–Martienssen tail, giving the characteristic phonon energy of 30 meV. The result indicates that few longitudinal optical phonons contribute to the exciton-phonon coupling even at room temperature. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119196

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Laser-beam-induced-current measurements have been used to characterize the extent of reactive ion etching (RIE) induced type conversion in vacancy-dopedp-type Hg0.69Cd0.31Te. The technique allows the spatial extent of RIE induced type conversion to be determined and the donor level concentration profile within then-type converted region to be estimated. For the RIE processing conditions used (410 mT, CH4/H2, 0.4 W/cm2)and an etch depth of 0.2&mgr;m,n-type conversion extending∼1.5&mgr;m into the semiconductor was observed. The simple and powerful approach developed in this work is of general application to the study of semiconductor junctions, and can be applied to a range of processing techniques used in the formation ofp-njunctions in HgCdTe (e.g., epitaxially grown heterojunctions, ion implantation, ion milling and Hg in-diffusion). ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119159

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The absolute photoyields of chemical vapor deposited (CVD) diamond and amorphous hydrogen-free diamondlike carbon (DLC) films, in the range of 140–300 nm, are reported. CVD diamond films exhibit a large photoyield, of a few percent in the range 140–180 nm. DLC films have a 20–50 times lower yield. Post growth hydrogenation is found to substantially increase the photoyield of CVD diamond films. We discuss the applicability of these films as UV photocathodes coupled to electron multipliers based on gaseous charge multiplication. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119197

出版商:AIP    

年代:1997

数据来源: AIP