摘要:

A matrix of Si crystals can be formed on amorphous substrates by manipulating nucleation sites. We have investigated various SiNxby x‐ray photon spectroscopy in order to search for suitable artificial nucleation sites and measured the density of Si nuclei deposited on the SiNx. It is found that the Si/N compositional ratio of the Si+ion implanted SiNxsurface is much higher than the theoretically estimated value. Si nucleus density on these surfaces increases with the Si/N compositional ratio. Si crystals were well manipulated on the portions of the Si‐enriched SiNxdotted over SiO2due to improved selectivity.

ISSN:0003-6951    

DOI:10.1063/1.102437

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We carried out transient optical absorption measurements of the conversion, induced by electron pulse irradiation, of the GaAs EL2 between the normal (EL20) and metastable (EL2*) states. It is found that no thermal barrier exists in the EL2* to EL20conversion when induced by electron pulse irradiation and that the yield of the EL20to EL2* conversion is much lower than that of the reverse conversion. These conversion processes were attributed to arise from the electron‐hole recombination at the EL2.

ISSN:0003-6951    

DOI:10.1063/1.101809

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We report that part of the InP‐anodic oxide interface states consists of bistable defects under two charge state configurations. Deep level transient spectroscopy measurements after positive, negative, or zero bias cooling of the samples from room temperature to 80 K are used. Slow states induced by defects in the anodic oxide layer are also characterized with a concentration in the range 1017–1018cm−3. The effect of the slow states on the bistable behavior is analyzed. This bistable behavior is related to the modification of the Fermi level pinning after some bias stresses.

ISSN:0003-6951    

DOI:10.1063/1.102438

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Growth of Ti‐doped In0.53Ga0.47As using liquid phase epitaxy is reported. The energy position of the Ti4+/Ti3+deep donor level in In0.53Ga0.47Asp‐ndiodes is precisely identified for the first time by deep level transient spectroscopy. The near midgap location of this level atEC−ET=0.37 eV and the potential of InGaAs:Ti of superior thermal stability make it a promising dopant for growing semi‐insulating In0.53Ga0.47As. A recent model suggesting the energy positions of transition metals not to vary across heterojunctions is tested and found to be at least qualitatively valid for this low spin transition metal.

ISSN:0003-6951    

DOI:10.1063/1.101810

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The atomic structure of the (111) interface between CoSi2(typeAandB) and Si is investigated by high‐resolution transmission electron microscopy, combined with image simulations. TypeBinterfaces of CoSi2layers formed by thermal reaction of vapor deposited Co on (111) oriented Si, of Si/CoSi2/Si heterostructures, and of CoSi2precipitates formed by high‐dose Co implantation were examined. The coordination of the Co atoms at allB‐type interfaces is found to be eightfold, in accordance with theoretical predictions. TypeAinterfaces of CoSi2precipitates and continuous CoSi2layers, formed by ion implantation and subsequent annealing, showed clear evidence for the presence of sevenfold coordinated interfacial Co.

ISSN:0003-6951    

DOI:10.1063/1.102439

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Intermixing of AlGaAs‐based interfaces is known to be enhanced by capping wafers with a layer of SiO2. Assuming that this enhancement results from the introduction of additional Ga vacancies into the sample, it is possible to obtain the temperature‐dependent equilibrium Ga vacancy diffusivity. Experiments are performed whereby SiO2‐capped quantum well samples are annealed at temperatures ranging from 800 to 1025 °C. Calculated photoluminescence shifts are compared with the measured spectra, and a relation for the Ga vacancy diffusivity of the form 0.962 exp(−2.72/kBT) cm2/s is obtained. Using this relation, the equilibrium Ga vacancy concentration can be computed via an ensemble Monte Carlo simulation. The resulting expression is 1.25×1031 exp(−3.28/kBT) cm−3.

ISSN:0003-6951    

DOI:10.1063/1.101811

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The threshold current and quantum efficiency are calculated for a far‐infrared injection laser, based on intersubband transitions in GaAs single quantum wells. By considering the balance of gain against the free carrier and transverse optical (TO) phonon absorption, and the intersubband transition time in the intermediate to the far infrared, the wavelength dependence of the threshold current is calculated. We find that for the wavelength range 50–120 &mgr;m, the required threshold currents are the lowest and have reasonable values of 103–104A/cm2. The threshold quantum efficiency in that range is expected to be ∼10−4.

ISSN:0003-6951    

DOI:10.1063/1.101812

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The results of an experimental apparatus and procedure using noise measurement techniques to identify conduction mechanisms in resonant tunneling diodes due to defect‐assisted tunneling are presented. The activation energies and capture cross sections of the traps are determined for each of three distinct levels detected. These values are in good agreement between the forward bias and inverted bias cases. A conjecture is made as to the physical location of the traps. This interpretation yields qualitative behavior consistent with the known bias and temperature dependence of the experimental results.

ISSN:0003-6951    

DOI:10.1063/1.101813

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We report the first demonstration of selective area crystallization of amorphous silicon films using low‐temperature rapid thermal annealing. Crystallization temperatures as low as 500 °C were achieved with the help of a thermally evaporated ultrathin metal layer. The selective area crystallization was accomplished by using this ultrathin metal layer to define the region to be crystallized. The edge between two regions, that which has been crystallized and that which has not, is found to be very sharp.

ISSN:0003-6951    

DOI:10.1063/1.101814

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A molecular beam epitaxial grown GaAs three‐terminal device with a delta‐doped barrier and GaInAs quantum well exhibiting controllable S‐shaped negative differential resistance and switching voltages has been fabricated and tested. The device has a large potential barrier between the anode and cathode regions which can be modulated via a third terminal. The modulation of the potential barrier has a substantial effect on the switching behavior of the device. For the devices having a cathode contact area of 50 &mgr;m2, a spectrum analyzer reveals unstable oscillation up to the system measurement limit of 21 GHz. The output power signal for the best device is greater than −10 dBm which is 20 dB above the noise floor at 20.8 GHz. The results show this device to be a potentially useful and promising high‐frequency oscillator.

ISSN:0003-6951    

DOI:10.1063/1.101815

出版商:AIP    

年代:1989

数据来源: AIP