摘要:

We have developed a prototype of a novel strain transducer. The change in magnetic reluctance in a ferromagnetic thorus with a gap due to the applied strain is detected by a superconducting magnetometer (SQUID). Strains as small as &Dgr;l/l=10−10have been detected on a bandwidth of 1 Hz up to 16.7 kHz in a reduced sensitivity version of the apparatus. Further experimentation at higher sensitivity with the present experimental setup is prevented by the background mechanical noise of the building.

ISSN:0003-6951    

DOI:10.1063/1.89349

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The electron drift‐velocity–electric‐field relationship has been calculated for the Ga1−xInxP1−yAsyquaternary alloy using the Monte Carlo method. Emphasis has been placed on the compositional range for which the alloy is lattice matched to GaAs and InP. These calculations suggest that this quaternary offers promise as a material for microwave semiconductor devices, including field‐effect transistors and transferred electron devices.

ISSN:0003-6951    

DOI:10.1063/1.89350

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A radiometric method for the measurement of the diffusion noise in homogeneous semiconductors is presented. The work has been carried out on epitaxies siliconn+nn+at room temperature, the electric field applied (1⩽E⩽70 kV/cm) being along the ⟨111⟩ direction. The results are in close agreement with those computed through the impedance field method with the high field diffusion coefficient values obtained by Canali who had used the time‐of‐flight technique.

ISSN:0003-6951    

DOI:10.1063/1.89351

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A comparison was made of the photoluminescent (PL) intensities ofn‐type InP and GaAs at room temperature. The PL intensity for InP was over 100 times greater than for comparably doped GaAs. The effect of surface recombination velocitySon the PL intensity was evaluated numerically. When this evaluation is applied to the PL intensity ratios ofn‐type InP and GaAs it shows thatSforn‐type InP is sufficiently small to eliminate significant influence of nonradiative surface recombination on the observed PL intensity.

ISSN:0003-6951    

DOI:10.1063/1.89352

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Vapor‐grown heteroepitaxial structures of GaAs0.7P0.3/In0.34Ga0.66P have been fabricated into double‐heterojunction laser diodes with room‐temperature threshold current densities as low as 3400 A/cm2at &lgr;L≃7000 A˚. This value is about three times less than the best reported for (Al,Ga)As lasers at this wavelength. From the (Ga,As)P/(In,Ga)P lattice‐matched structures, cw operation at 10 °C has been achieved.

ISSN:0003-6951    

DOI:10.1063/1.89353

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

We propose and demonstrate that the photoacoustic effect can be used for absolute determination of the optical absorption coefficient. The photoacoustic signal is measured as a function of chopping frequency and compared to the theory of the photoacoustic effect. The essential agreement of theory and experiment over a restricted frequency makes possible the determination of the optical absorption coefficient (to within 10% in a test case). Observation of a characteristic leveling off of the photoacoustic signal at low frequencies for several materials is also reported.

ISSN:0003-6951    

DOI:10.1063/1.89354

出版商:AIP    

年代:1977

数据来源: AIP