摘要:

We describe a technique using photolithography to produce submicron‐scale thin‐film structures and simple multilevel structures by single‐mask lift‐off processing. The technique employs masks offset from the substrate and oblique angle thin‐film deposition. It provides a simple means of making small‐area Josephson junctions and varying‐thickness superconducting bridges and is suitable for the inclusion of these devices in circuits. The examples we show emphasize such applications in superconductivity; however, the technique may find uses in other fields as well.

ISSN:0003-6951    

DOI:10.1063/1.89690

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The high‐field domains in a Gunn‐effect diode triggered at 1 GHz have been studied pictorially with the stroboscopic scanning electron microscope.Y‐modulated images have also been obtained.

ISSN:0003-6951    

DOI:10.1063/1.89691

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

In order to calibrate previous secondary ion mass spectrometry (SIMS) measurements on various oxidized metal surfaces in terms of oxygen coverage, quasisimultaneous SIMS, AES, and XPS have been applied to several metal‐oxygen systems. First, results are given for the Ti‐O system. In this case, the oxygen signals obtained with the three methods show an identical dependence on the oxygen exposure and can therefore be used for establishing a coverage scale. The successive stages of oxidation lead to significant changes of first the AES, then the SIMS signals, and finally a chemical shift in XPS.

ISSN:0003-6951    

DOI:10.1063/1.89692

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A procedure for reducing the interstitial oxygen content of virgin Czochralski silicon wafers is described. The process consists of oxidizing wafers in an HCl‐added dry oxygen ambient. The gettering action reduces the probability of oxygen precipitation throughout the bulk of the wafer and simultaneously provides a masking or passivating surface oxide. Since oxygen precipitates have been correlated with the nucleation of dislocations and stacking faults, which are known to adversely affect many devices, these gettering procedures may provide a means for overcoming some of the processing problems associated with large‐diameter high oxygen content Czochralski material.

ISSN:0003-6951    

DOI:10.1063/1.89693

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The recombination kinetics in highly dopedp‐ andn‐type silicon has been investigated at 77, 300, and 400 K through the radiative band‐to‐band recombination. The minority‐carrier lifetime depends quadratically on the doping concentration as expected for Auger recombination. The Auger coefficients at 300 K forp‐ andn‐type silicon are found to beCp=9.9×10−32cm6 s−1andCn=2.8×10−31cm6 s−1. They are nearly independent of temperature in the range investigated. The Auger coefficient in highly excited pure silicon at 4.2 K (electron‐hole drops) is essentially the same as in highly doped silicon.

ISSN:0003-6951    

DOI:10.1063/1.89694

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A new method is proposed to estimate interface state density in hysteretic MIS devices. In this method, a narrow bias‐voltage swing is applied around a certain center bias voltage to obtain a narrowC‐Vcurve without hysteresis. It is shown that the capacitance derivative obtained in this way depends on MIS capacitance only, and then can be used for determining the interface state density in the hysteretic InSb MIS devices.

ISSN:0003-6951    

DOI:10.1063/1.89695

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A long‐lifetime (&tgr;∼hours,T≲60 °K) photoconductivity effect is observed in Te‐doped Ga1−xAlxAs (0.25≲x≲0.7). Analysis of Hall‐effect data showing a pronounced decrease in the electron mobility upon photoexcitation shows that a donor level is involved. Similar effects are observed in Se‐ and Sn‐doped Ga1−xAlxAs (x=0.3). The magnitude of the effect which is typically of the order of the room‐temperature electron concentration seems to correlate linearly with the concentration of Te, showing that a constant concentration background impurity is not responsible for this effect. A large lattice relaxation is indicated by the large difference between the thermal (0.12 eV) and optical (1.1 eV) ionization energy of the donor level. The potential barrier to electron capture by the donor level is estimated to be 180 meV (x=0.36) from time decay measurements of the photoexcited electron population at low temperatures. Extrapolation to room temperature gives a characteristic decay time of ∼0.5 nsec for the electron concentrations expected in injection lasers.

ISSN:0003-6951    

DOI:10.1063/1.89696

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

An important function in semiconductor‐device analysis and transport theory is the widely tabulated Fermi‐Dirac integral,F(&eegr;) =2&pgr;−1/2F∞0[exp(x−&eegr;)+1]−1f dx,f=x1/2, which relates, for example, the Fermi energy &eegr;kTto the carrier densityN=FN0in a parabolic semiconductor band (N0=effective density of states). We show that the classical or Boltzmann approximation to this integral (&eegr;=lnF, &eegr;≲−2) is extended to cover the Fermi‐energy range of semiconductor lasers (&eegr;≲+2) by the expression &eegr;=lnF+2−3/2Fand by other simple differentiable approximations applicable to higher degeneracy (&eegr;≲7) or to nonparabolic bands (f≠x1/2).

ISSN:0003-6951    

DOI:10.1063/1.89697

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A model is developed for the incorporation of donors and acceptors in epitaxial GaAs which indicates that the thinp‐type region often observed at the layer‐substrate interface inn−p+ structures is caused by the electric field associated with surface states and substrate doping. The model also predicts impurity gradients at the outer surface, about which little is known experimentally. Since results from the model are in agreement with many experimental observations, surface states and substrate doping are believed to be the major cause of impurity gradients in epitaxial GaAs.

ISSN:0003-6951    

DOI:10.1063/1.89698

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The double‐junction SQUID is viewed as a parametric amplifier and mechanisms, which place an upper limit on the pump frequency (and thus gain), are investigated. Self‐induced steps in theI‐Vcharacteristics as well as damping of the Josephson oscillation are shown to be two limiting mechanisms.

ISSN:0003-6951    

DOI:10.1063/1.89699

出版商:AIP    

年代:1977

数据来源: AIP