摘要:

By measuring the time‐dependent optical reflectivity, we have investigated the dynamic behavior of annealing with the 30‐psec pulse train of a mode‐locked Nd : YAG laser. It was first observed that at narrow ranges of high laser energy density, the reflectivity of implanted Si and GaAs increases slowly to the level consistent with liquid ones, except GaP, and remains at that level for a period less than 200 nsec. As to Si, the mode‐locked laser is confirmed to have a weak effect on temperature rise and, therefore, to produce a thin molten layer compared toQ‐switched Nd : YAG lasers.

ISSN:0003-6951    

DOI:10.1063/1.91231

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Pulsed electron beam annealing has been used to activate high‐dose silicon implants in InP. Peak concentrations ≳ 1019cm−3are obtained without any appreciable carrier freezeout on cooling to 78 °K. Such activation is comparable to that obtained on thermal annealing and is seen on samples implanted at both room temperature (amorphous) and 200 °C. In common with the behavior reported for GaAs, the mobility is similarly curtailed below thermally annealing values. Though the initial polished appearance is generally retained, unusual thermal oxidation and anodization properties suggest the possibility of surface phosphorous loss.

ISSN:0003-6951    

DOI:10.1063/1.91232

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Laser annealing of nitrogen implanted AlxGa1−xAs was carried out by using an Ar+laser. A reliable and well‐controlled annealing was performed with threshold power density of the order of 105W/cm2. Photoluminescence (PL) characteristics show that laser annealing is superior to thermal annealing in terms of PL intensities and the absence of deep levels. New emission bands were obtained at the intermediate power density of the laser, which were never obtained in thermal annealing.

ISSN:0003-6951    

DOI:10.1063/1.91233

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Carrier recombination in heavily doped semiconductors via shallow donor or acceptor states is analyzed. The results are in general agreement with experimental lifetime observations including the 1/n20or 1/P20dependence, and the insensitivity to temperature and to the dopant used. Capture cross sections of about 10−20cm2needed to fit the lifetime data are reasonable for neutral traps and are consistent with low‐temperature capture cross sections reported for shallow dopants.

ISSN:0003-6951    

DOI:10.1063/1.91234

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Some narrow‐gap mixed crystal semiconductors show a magnetic field induced transport anomaly at low temperatures. The anomaly is accompanied by a transition from a low to a high resistivity state, which in turn causes a strongly nonlinearI‐Vcharacteristic. We have investigated microwave mixing near such a phase transition inn‐type Hg0.8Cd0.2Te with a frequency of 37 GHz at 1.5 K and in magnetic fields up to 8.5 T. The sensitivity characteristic was measured and the responsivity determined to be about 15 times higher than that of a hot‐carrier InSb bolometer. The time resolution of this new bolometer (=10−7s) was slightly better than in InSb.

ISSN:0003-6951    

DOI:10.1063/1.91235

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

An experimental method to measure the imaginary and real part of the input impedance of an rf biased SQUID is described. The experimental results are in good agreement with the predictions of a detailed theoretical model of the rf SQUID, recently published. In particular it seems confirmed that the real part of the input impedance has a negative value which depends on the square of the input signal frequency. This effect must be taken into account whenever a SQUID is used to measure high frequency signals.

ISSN:0003-6951    

DOI:10.1063/1.91236

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The backscattered electron (BSE) signal in the scanning electron microscope (SEM) can be modulated, under the proper experimental conditions, by magnetic fields inside the specimen. This modulation is typically less than 1% of the collected current, and this must be amplified so as to be clearly visible in the recorded image. We have found that unwanted topographic contrasts can be reduced in comparison with this magnetic contrast by a lock‐in technique. With a 1‐&mgr;m permalloy film as the sample, the domain walls can be moved repetitively by applying a sinusoidal magnetic field. If the video waveform is processed using a lock‐in amplifier controlled by this same signal, then the portions of the domain walls that move are emphasized in the image. Parts of the image which are not affected by the modulating magnetic field are strongly attenuated in the processed image.

ISSN:0003-6951    

DOI:10.1063/1.91237

出版商:AIP    

年代:1979

数据来源: AIP

ISSN:0003-6951    

DOI:10.1063/1.91272

出版商:AIP    

年代:1979

数据来源: AIP