摘要:

The manufacturing of interconnect features on semiconductor wafers has evolved from lift-off-based evaporation to reactive ion etching metallization and now to Damascene technology. Physical sputter deposition has been widely used for blanket metal film deposition, but is impractical for high aspect topographies. Filtered, or directional sputter techniques, such as long throw or collimation, have been used for some high aspect ratio applications, but suffer from poor efficiency, high cost, and/or poor scaling. Ionized sputter deposition, which uses in-flight ionization of sputtered metal atoms and subsequent film deposition by means of a substrate potential, has been developed as a technique to extend physical vapor deposition into higher aspect ratios.

ISSN:1071-1023    

DOI:10.1116/1.590242

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Over the last few years, SiGe heterodevices with outstanding rf performance have been introduced to meet the needs of modern consumer electronics, which require novel silicon-based low cost–high speed components with improved current gain, low noise, and reduced power consumption operating in the GHz range. This article reviews device and the first circuit results of lateral modulation doped SiGe modulation doped hetero-field-effect transistors (MODFETs) with Schottky gates as well as lateral and vertical SiGe metalorganic field effect transistors (MOSFETs) focusing on dc characteristics, rf performance comprising cutoff frequencies, delays, and on layer design. With anfmax,of up to 92 GHz, the highest maximum frequency of oscillation reported so far for any Si-based FET, and transconductancesgmeup to 470 mS/mm, then-SiGeMODFET is presently improving in speed with combining the advantages of heterodevices with well-established Si technology. Forp-SiGeMODFETs cutoff frequenciesftof 70 GHz andfmaxof 84 GHz have been measured. A reduced gate leakage and an improved voltage swing is achieved using MOS-gated heterodevices. Forp-channel SiGe hetero-MOSFETs room temperature transconductances up to 210 mS/mm for 0.25 μm gate-length devices have been measured. Vertical MOSFETs allow further device scaling into the deep sub-100 nm range and thus enable us to overcome performance limits due to minimum feature sizes using state-of-the-art lithography techniques.

ISSN:1071-1023    

DOI:10.1116/1.590236

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

We have performed photo- and electroluminescence measurements on erbium doped silicon and SiGe samples containing different amounts of germanium. All samples were grown completely by molecular beam epitaxy. Oxygen was used as a codopant to enhance the luminescence efficiency. The photoluminescence data show a systematic variation of the thermal activation energy obtained from temperature dependent intensity measurements with varying germanium contents. For samples with an alternating Si/SiGe layer structure stronger photoluminescence is observed when the erbium ions are incorporated into the SiGe layers rather than into the silicon layers. We attribute this to the capture of photogenerated carriers in the SiGe layers. Electroluminescence from erbium doped SiGe samples which have been processed as diodes has been observed up to room temperature in both surface and edge emitting geometries.

ISSN:1071-1023    

DOI:10.1116/1.590243

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

We present a voltage-tunable wavelength-selective photodetector (VWP) for the near-infrared (NIR), realized by engineering the optical properties of Si and Ge. The structure exhibits a wide tunability by varying the applied voltage and weighting the photocurrents generated by two back-to-back diodes. We demonstrate its versatility in deconvolving signals of different wavelengths and a preliminary study on the applications of the VWP as a solid-state spectrum analyzer. The spectrum of NIR light impinging the device can be resolved from a set of photocurrent measurements for different bias voltages.

ISSN:1071-1023    

DOI:10.1116/1.590244

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Solid-phase reaction, Schottky barrier heights and contact resistivities at the interface ofTi/Si0.8Ge0.2/Si(100)systems have been investigated. At annealing temperatures below 300 °C, Ti atoms preferentially react with Si atoms. Ge atoms start to react with Ti above 400 °C andC54–Ti(Si1−yGey)2with a fraction ofy=0.12is formed by annealing at 650 °C. The annealing behavior of Schottky barrier heights suggests that the Ge composition of SiGe layers at the interface is Si-rich, which is consistent with the results on the interfacial reaction. For bothn- andp-SiGe, the Schottky barrier heights lower than those of Ti/Si(100) are obtained at 650 °C, which is considered to be related to the reaction product such asC54–Ti(Si1−yGey)2.The contact resistivities smaller than those expected from the Schottky barrier heights are obtained forp+-SiGe at 580 °C. The sheet resistance ofTi/Si0.8Ge0.2/Si(100)and Ti/Ge(100) systems decreases at annealing temperatures above 550 °C and the values are as small as that ofC54–TiSi2.

ISSN:1071-1023    

DOI:10.1116/1.590245

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Si1−xGex/Siheterostructures were formed on Si(100) wafers by using single-energyGe+implantation, doubleSi+andGe+implantations, or doubleGe+andGe2+implantations. Both near surface (hairpin dislocations) and end-of-range (EOR) damage (dislocation loops) were found. At high doses, EOR damage was found beyond the original amorphous/crystalline(a/c)interfaces after annealing. The double implantation processes using low energy and high doseGe+implantation to form a compositionally graded SiGe alloy layer, or using a high energy and low doseSi+orGe2+implantation to form a deep amorphous layer, caused a spatial separation between the Ge maximum anda/cinterface. Subsequent solid phase epitaxy anneals localized the EOR beyond the peak Ge positions. Rutherford backscattering spectroscopy channeling measurements confirm that the double-energyGe+/Ge2+method led to the fewest residual defects.

ISSN:1071-1023    

DOI:10.1116/1.590246

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The effect of Te presence on the morphology and distribution of InAs islands grown by molecular beam epitaxy on GaAs is investigated. Atomic force microscopy was used to follow the dependence of height, radius, and surface density on Te and InAs coverages. They ranged from zero to 0.45 monolayers (ML) of Te, and from 1.8 to 3.5 ML for InAs. We obtained a higher density of islands for samples covered with 0.3 ML of Te. The number of islands is essentially the same for samples covered with 0 and 0.45 ML of Te. A delay on the onset of island growth is observed for samples withθTe=0.45 ML.The surface morphology is also different for samples with Te when compared with the Te free sample. We suggest that forθTe=0.45 MLthe coherence-incoherence transition is either delayed or absent for the InAs coverage range studied.

ISSN:1071-1023    

DOI:10.1116/1.590247

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The crystalline quality of tensile strainedGa0.25In0.75Players grown on InP substrates was investigated. The samples were grown by metalorganic molecular beam epitaxy. Little or no relaxation was found inGa0.25In0.75Players which were up to 500 Å thick. The relaxation of layers less than 700 Å thick was isotropic, but thicker (bulk-like) layers relaxed anisotropically, with the main relaxation along the [11̄0] direction. Fully strained layers up to a thickness of 650 Å were obtained by employing strain compensation. Heterostructure field effect transistors (HFETs) incorporating a tensile 200 Å thickGa0.25In0.75Pbarrier were fabricated. A composite channel of compressive strainedGa0.3In0.7Asand lattice matched GaInAs was used to compensate the tensile strained barrier. The HFET channel was partially doped. A peak transconductance of 200 mS/mm was obtained in HFETs having a 1 μm long gate. The drain-source breakdown voltage was 10 V, and gate-drain breakdown voltage was 11 V. The unity current gain frequency,fT,and the maximum frequency of oscillation,fmax,were 23.5 and 50 GHz, respectively. Resonant tunneling diodes withGa0.25In0.75Pbarriers and aGa0.47In0.53Aswell were demonstrated as well. Peak to valley current ratios of 1.15 and 5 were obtained at room temperature and 77 K, respectively.

ISSN:1071-1023    

DOI:10.1116/1.590248

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

We investigated InAs deep quantum well structures (InAs QWs) made from InAs/AlGaAsSb materials on GaAs substrates by molecular beam epitaxy. In the InAs QWs, AlGaAsSb layers were lattice matched to InAs. Using reflection high-energy electron diffraction (RHEED) linescan images analysis, we show that AlGaAsSb on GaAs surfaces quickly relaxes within 3–7 monolayers (MLs). The initial stages of AlGaAsSb growth on GaAs(100) substrates and InAs growth on AlGaAsSb layers have been investigated by atomic force microscopy (AFM) and RHEED image analysis. A new growth mode, exhibiting ridgeline shapes during the initial stages of GaAsSb and AlGaAsSb growth on GaAs surfaces, was observed. At the interface of the InAs/AlGaAsSb, the two-dimensional growth of InAs was observed. The roughness at the InAs/AlGaAsSb interface was 3–4 MLs from AFM, high-resolution transmission electron microscopy and grazing incidence x-ray reflectivity analyses. We achieved very high electron mobilities of 32 000 cm2/V s at room temperature using a thin buffer layer of 600 nm AlGaAsSb.

ISSN:1071-1023    

DOI:10.1116/1.590249

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

A systematic investigation on the mechanisms of nucleation and surface morphology evolution was performed on ZnTe epilayers, deposited on chemically etched GaAs(001) by metalorganic vapor phase epitaxy. A 2D–3D growth mode transition was observed at around two ZnTe equivalent monolyers (ML), which was ascribed to a Stransky–Krastanow growth mode. The 3D growth behavior was correlated to the development of{n11}-type planes, leading to a surface ridging effect along the [11̄0] direction for 4000-ML-thick ZnTe epilayers. The use of a solid-on- solid kinetic roughening model allowed the identification of a mechanism that limits the self- organization of ZnTe nanosized islands, namely, the high density of kink sites found in non- atomically flat GaAs substrates.

ISSN:1071-1023    

DOI:10.1116/1.590250

出版商:American Vacuum Society    

年代:1998

数据来源: AIP