摘要:

Experimental measurements of critical layer thicknesses (CLT’s) in strained‐layer epitaxy are considered. Finite experimental resolution can have a major effect on measured CLT’s and can easily lead to spurious results. The theoretical approach to critical layer thicknesses of J. W. Matthews [J. Vac. Sci. Technol.12, 126 (1975)] has been modified in a straightforward way to predict theapparentcritical thickness for an experiment with finite resolution in lattice parameter. The theory has also been modified to account for the general empirical result that fewer misfit dislocations are generated than predicted by equilibrium calculation. The resulting expression is fit to recent x‐ray diffraction data on InGaAs/GaAs and SiGe/Si. The results suggest that CLT’s in these systems may not be significantly larger than predicted by equilibrium theory, in agreement with high‐resolution measurements.

ISSN:0003-6951    

DOI:10.1063/1.98746

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The use of a reactive ion etch process with high selectivity for etching GaAs layers and stopping on underlying AlGaAs layers is reported. A key feature is the high degree of control that can be maintained over the GaAs‐to‐AlGaAs selectivity by changing the SF6/SiCl4ratio while keeping other etch parameters such as pressure, dc bias, or power constant. Values of the GaAs‐to‐AlGaAs selectivity can be varied from 1 to 500. Diluent gases such as helium can be added to reduce the etch rate, which is important to avoid damage to sensitive device structures and to the overhang profile of resist materials used for liftoff metallization. The application of this etch process for high electron mobility transistor fabrication is discussed.

ISSN:0003-6951    

DOI:10.1063/1.98747

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Injection mode infrared detector concepts are expanded to incorporate the nonlinear dynamics concept of mode locking. The first successful demonstration of this approach is reported. The detectors employ extrinsic silicon and have large output signals which require no electronic amplification. Mode locking greatly reduces fluctuations in detector output without a corresponding reduction in detector responsivity. The results could lead to the development of a new class of sensors which exploit recent work on the distinction between deterministic fluctuations in nonlinear systems and intrinsic noise.

ISSN:0003-6951    

DOI:10.1063/1.98748

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The lifetime of the lowest quasibound state localized between the barriers of a GaAs/AlGaAs double‐barrier structure is calculated as a function of barrier and well dimensions. The results are consistent with high‐frequency experiments.

ISSN:0003-6951    

DOI:10.1063/1.98749

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

In this letter we present experimental and theoretical results for excitonic transitions in coherently strained GaAs/InGaAlAs multiquantum well structures grown on a GaAs substrate. Absorption spectra of the structure with the substrate removed show an extremely sharp exciton peak with an absorption constant corresponding to nearly twice the value of that in the lattice‐matched GaAs/AlGaAs system. Theoretical calculations suggest that the biaxial tensile strain in the well region, occurring after the substrate is removed, causes the heavy‐hole and light‐hole exciton states to coincide for a specific composition of the quaternary alloy. A comparison between the experiments and theory is made and the potential for devices based on this phenomenon is discussed.

ISSN:0003-6951    

DOI:10.1063/1.98750

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Bias stress measurements on amorphous silicon‐silicon nitride ambipolar thin‐film transistors give clear evidence for the co‐existence of two distinct instability mechanisms: the metastable creation of states in thea‐Si:H layer and charge trapping in thea‐SiN:H layer. The creation of metastable states in thea‐Si:H is found to dominate at low positive bias, while charge trapping in the nitride dominates at larger positive bias and negative bias.

ISSN:0003-6951    

DOI:10.1063/1.98751

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We report the millimeter‐wave performance of enhancement mode InP metal‐insulator‐semiconductor field‐effect transistors grown by chloride vapor phase epitaxy. For a gate length of 1 &mgr;m we have measured a current gain cutoff frequency of 29 GHz and an electron velocity of 2.5×107cm/s, close to a theoretical current gain cutoff frequency of 40 GHz. This represents the fastest InP‐based field‐effect transistor ever demonstrated, and surpasses state‐of‐the‐art AlGaAs/GaAs modulation‐doped field‐effect transistors having similar gate length.

ISSN:0003-6951    

DOI:10.1063/1.98752

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The formation of TiSi2thin films on Si has been investigated byinsitux‐ray diffraction and electrical transport. The x‐ray results show unequivocally that the staging proceeds through two orthorhombic polytypes of TiSi2according to the sequence: sputter‐deposited metallic Ti or TiSixalloy films on Si(001)→TiSi2(C49 structure)→TiSi2(C54 structure), with no evidence of lower silicides. Electrical transport shows metallic behavior for all phases and distinctive features in the annealing curves which correlate with the structural transformations. Most important, the resistivity, characteristically very high for the C49 phase, undergoes a precipitous drop at the C49→C54 transition. In the C54 phase when fully annealed the resistivity is 12.4 &mgr;&OHgr; cm at room temperature and 0.66 &mgr;&OHgr; cm at 4.2 K.

ISSN:0003-6951    

DOI:10.1063/1.98753

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

An electron paramagnetic resonance spectrum, observed in electron irradiated silicon and labeledSi‐G15, is shown to originate from the same carbon‐oxygen complex as does the well studied C‐line photoluminescence spectrum with zero‐phonon line at 0.79 eV. Both thegtensor and the13C hyperfine tensor for this center are remarkably similar to those for the isolated interstitial carbon atom. Stress‐induced alignment experiments reveal the role of oxygen and indicate a unique structure for an interstitial carbon‐interstitial oxygen pair.

ISSN:0003-6951    

DOI:10.1063/1.98754

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We report on the formation of nickel silicide in nickel‐implanted amorphous silicon thin films. We have found that during annealing, precipitates of NiSi2form in the interior of the film. This is in contrast with results for interfacial reactions between nickel films and silicon, where the first phases to appear are Ni2Si and NiSi on amorphous silicon, and Ni2Si on crystalline silicon. We suggest that these results reflect differences in surface energies and their effects on silicide nucleation.

ISSN:0003-6951    

DOI:10.1063/1.99003

出版商:AIP    

年代:1987

数据来源: AIP