摘要:

The specific contact resistivity and the Schottky barrier height in the Zr/Si system have been measured as a function of annealing temperature. The specific contact resistivity decreases with increasing annealing temperature and a minimum value of 4×10−8&OHgr; cm2is obtained after annealing at 420 °C in a vacuum, which is about two orders of magnitude lower than that of the Al (1.5% Si)/n+‐Si system. The formation of ZrSi2is observed at annealing temperatures above 350 °C, which can be considered to be related to the lowering of contact resistance. The Schottky barrier heights of as‐grown Zr films are 0.61 eV forp‐type Si and 0.52 eV forn‐type Si.

ISSN:0003-6951    

DOI:10.1063/1.103505

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Epitaxial CdTe (100) has been grown on (100)orientedSiby molecular beam epitaxy using BaF2‐CaF2as a buffer. Two‐dimensional (2‐D) growth of BaF2(100) is obtained using low‐temperature thermal cycles during growth. CdTe growth is also 2‐D above 270 °C substrate temperature and a 2×1 surface reconstruction indicating a Te‐stabilized surface is obtained. The growth is 3‐D at lower substrate temperatures. Good structural quality films showing sharp electron channeling patterns and pronounced photoluminescence at 77 K are obtained. The full width at half maximum of the band‐edge peak is 12 meV at 77 K.

ISSN:0003-6951    

DOI:10.1063/1.103506

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Schottky barrier PtSi‐Si diodes formed by ultrahigh vacuum deposition and annealing of 1‐nm‐thick Pt films onn‐ andp‐type (100) Si substrates were characterized by current‐voltage measurements at liquid‐nitrogen temperature. The diodes exhibited nearly ideal characteristics, with barrier heights of 0.914 and 0.197 eV, respectively, for typicaln‐ andp‐type devices. Subsequent annealing in hydrogen increased the barrier height by 0.013 eV for then‐type devices and decreased it by the same amount for thep‐type devices. Vacuum annealing of H2‐annealed devices restored the barrier heights to approximately their initial values. These results can be attributed to the presence of Si interface defects that are passivated by hydrogen incorporation and subsequently reactivated by vacuum annealing to remove the hydrogen.

ISSN:0003-6951    

DOI:10.1063/1.103507

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Random variations in the well widths of a superlattice structure are shown theoretically to result in band structure features which mimic amorphous materials. In direct analogy to uniform superlattices in which the periodic potential results in minibands, a randomly varying potential within a superlattice, arising from random variations in well width, gives rise to the formation of states within the miniband gap resembling band tailing effects. Calculations are made of the electron transmissivity through the superlattice based on the effective mass solution of the Schro¨dinger equation. Superlattice structures consisting of 30 wells of both randomly varying and uniform width are studied. Random variations governed both by a Poisson and a uniform distribution are analyzed. A possible new switching device based on the Ovshinsky effect [Phys. Rev. Lett.21, 1450 (1968)] is proposed.

ISSN:0003-6951    

DOI:10.1063/1.104098

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have investigated the transport properties of two‐dimensional electron systems in strained InxGa1−xAs channels confined in a potential well formed by delta doping and GaAs barriers. The dependence of the transport parameters on the indium composition has been studied using Hall, Shubnikov–de Haas, and cyclotron resonance measurements. Experimental measurements of the effective mass have been compared with theoretical data obtained from self‐consistent calculations, which take account of effects due to biaxial strain and nonparabolicity on the band structure of InxGa1−xAs.

ISSN:0003-6951    

DOI:10.1063/1.103508

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Epitaxial layers of GaAs with peak mobilities as high as 200 000 cm2/V s at 50 K have been grown in an atmospheric pressure organometallic vapor phase epitaxy reactor using trimethylgallium (TMG) and arsine. The growth conditions which lead to high‐mobility GaAs are described in this letter. Low‐temperature photoluminescence and temperature‐dependent Hall measurements are used to study the dependence of the incorporation of residual impurities on the growth temperature and arsine partial pressure. Carbon acceptor densities <1014cm−3were measured in the highest purity samples.

ISSN:0003-6951    

DOI:10.1063/1.103509

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We demonstrate subpicosecond electrical pulse propagation using coplanar air‐transmission lines. Rise times of 0.8 ps after 2.8 mm of propagation are achieved with a velocity of propagation which is 86% of the speed of light in vacuum. Our results suggest that intrachip communication in digital circuits with rise times as short as 1 ps is readily achievable using electrical signals.

ISSN:0003-6951    

DOI:10.1063/1.103510

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Detailed analysis of a buried layer of GaAs in ⟨100⟩ Si was carried out using electron energy loss spectroscopy, Rutherford backscattering spectroscopy, and ion channeling. The layer was formed by 200 keV dual ion implantation of Ga plus As ions, followed by furnace annealing at 600 and 950 °C. It consists of GaAs particles which are surrounded by fully recrystallized silicon. Beneath it is a dislocation network, made up of a mixture of edge and screw dislocations.

ISSN:0003-6951    

DOI:10.1063/1.103511

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

It is demonstrated using rapid thermal annealing that the electrical activation of Si+‐implanted GaAs capped with a plasma‐enhanced chemical vapor deposited (PECVD) silicon nitride (SixNy) layer requires longer annealing times compared to capless annealing. The SIMS profiles of2H from the GaAs samples onto which SixNycaps were deposited using deuterated ammonia showed that deuterium atoms diffuse readily into the implanted region during PECVD. The improvement in the electrical activation of the capped samples with annealing time correlates directly with decreasing concentration of the2H in the GaAs. It is postulated that the H atoms diffusing into GaAs during PECVD are trapped by the implantation‐induced damage and the delay in electrical activation corresponds to the time required for the release of the trapped H.

ISSN:0003-6951    

DOI:10.1063/1.103512

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We present the first measurements of room‐temperature excitonic absorption saturation in a II‐VI semiconductor quantum well. Strong room‐temperature excitonic absorption in CdZnTe/ZnTe quantum wells is found to saturate at an incident optical intensity that is considerably higher than that for III‐V quantum wells. We show that this phenomenon can be interpreted in terms of the smaller excitonic Bohr radius characteristic of wide‐gap II‐VI compounds.

ISSN:0003-6951    

DOI:10.1063/1.103513

出版商:AIP    

年代:1990

数据来源: AIP