摘要:

Based on a simple model of the band‐to‐band absorption of a diode laser active region, we formulatean expression for modal gain as a function of pumping current. Using this result yields expressions for threshold current density and lasing photon energy which depend on device parameters including active region thickness, laser length, internal losses, facet reflectivity, etc.

ISSN:0003-6951    

DOI:10.1063/1.93954

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

An undercut mesa laser is fabricated on ann+‐InP substrate using a single step liquid phase epitaxy growth process and a planar structure is obtained by using a polyimide filling layer. The lasers operate at fundamental transverse mode due to a scattering loss mechanism. Threshold currents of 18 mA and stable single transverse mode operating at high currents are obtained.

ISSN:0003-6951    

DOI:10.1063/1.93955

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

High optical power cw operation has been achieved at the wavelength range of 780 nm by newly developed window V‐channeled substrate inner stripe lasers. This laser consists of a waveguiding window region with a plane active layer and a stimulated region with a crescent active layer. These two regions are coupled to each other. cw optical power over 70 mW and low cw threshold current of 30 mA were obtained. Moreover, the fundamental transverse mode was observed up to 60 mW, and it was found that the beam waist along the junction existed at the mirror.

ISSN:0003-6951    

DOI:10.1063/1.93956

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Photodecomposition of organometallic gases has been shown to be potentially useful for high resolution direct metal deposition. However, a number of problems, particularly the low writing rates, must first be solved. An understanding of the deposition mechanism is essential to this task. In particular, the decomposition must be shown to occur either in the gas phase or in the adsorbed layer. We show that this question can be resolved by the dependence of the writing rate on spot size. Measurements of the process show that the decomposition occurs in the gas phase. This result is shown to cause inhomogeneous deposition for exposures through masks with varying feature sizes, and effect will be important to future applications.

ISSN:0003-6951    

DOI:10.1063/1.93957

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

When the scanning acoustic microscope is used in a defocussed mode to measure surface acoustic wave properties, circular surface wave fronts are generated on the specimen which propagate to a diffraction‐limited focus. Thus, high resolution surface wave images are simply formed and a wide range of established nondestructive testing techniques become available to the acoustic microscope. Images obtained in the reflection mode are presented which demonstrate the unexpectedly high spatial resolution.

ISSN:0003-6951    

DOI:10.1063/1.93958

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A directional acoustic microscope is described that has enhanced contrast for elastically anisotropic materials. Directional detection of surface acoustic waves by the acoustic lens is demonstrated on (100) and (111) silicon crystals. The grains of a polycrystalline silicon sample have contrast which varies as a function of lens orientation. Symmetry of contrast variations and measurement of surface wave phase velocity may provide a new way to determine the orientation of microscopic grains.

ISSN:0003-6951    

DOI:10.1063/1.93959

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The rf impedance of a dry etching system excited at 13.56 MHz is calculated from the settings of the matching network between the generator and the reactor. It is demonstrated that fundamental plasma parameters, which are useful in the evaluation of dry etching techniques, can be derived from these measurements. For an oxygen discharge at 27 Pa and 350 W m−2the following parameter values are obtained: maximum ion bombardment energy 76 V, electron density in the glow 5×1014m−3, ion flux density on the substrates 0.08 A m−2.

ISSN:0003-6951    

DOI:10.1063/1.93948

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

We compare the longitudinal and radial distributions of EL2 in undoped semi‐insulating and intentionally dopedn‐type GaAs crystals grown by the liquid encapsulated Czochralski technique. Longitudinal profiles in undoped crystals are controlled by changes in melt stoichiometry as the crystal is pulled from the melt. EL2 profiles along crystals doped above about 1×1017cm−3, on the other hand, are controlled primarily by the carrier concentration as a result of the suppression of EL2 by free electrons. Radial EL2 profiles are typically W shaped and M shaped in undoped and doped (above threshold) crystals, respectively. The origin of these radial profiles is discussed in terms of residual stress, melt stoichiometry, and the suppression of EL2 by electrons. Our results are also discussed in the light of the antisite model for EL2.

ISSN:0003-6951    

DOI:10.1063/1.93949

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

High‐intensity x radiation from the Stanford Synchrotron Radiation Laboratory storage ring has been used in a small‐angle scattering mode to study dynamic deformation behavior in polymers. Complete scattering curves were obtained as a function of time during relaxation with the strain direction oriented parallel and perpendicular to the plane of measurement. Interpretation is made of the resulting information on relative number, size, and time dependence of heterogeneities. A tentative model proposes that the application of stress starts a rapid creation of approximately uniform spherical voids which migrate and coalesce to form crazes and relieve the stress.

ISSN:0003-6951    

DOI:10.1063/1.93950

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

This letter presents new experimental evidence of periodic structure or ripples which occur on the surface of crystalline or ion‐implanted gallium arsenide in laser annealing. A new kind of ripple, whose direction does not depend on the electric field vector of the laser beam, appears for the larger angle of incidence between the laser beam direction and the surface normal. The variation in this ripple spacing with the incident angle of the laser beam to the surface normal is different from that for previously reported ripples, whose direction is always found to be almost perpendicular to the electric field vector for the linearly polarized laser beam. We suggest that the spacing for the new ripples can be interpreted from the reinforcement of the initially induced weak and straggling surface disturbances caused by the interference between the incident laser beam and succesively scattered waves.

ISSN:0003-6951    

DOI:10.1063/1.93951

出版商:AIP    

年代:1983

数据来源: AIP