摘要:

A vapor-deposited GaS passivating layer is formed on GaAs(100) withα-Ga2S3powder used as a single-source precursor for the deposition. The films grown show near-single-crystal quality, and are characterized by Auger electron spectroscopy and x-ray diffraction spectroscopy. The band-edge discontinuities of the GaS/GaAs heterojunction are determined to be 1.9 eV for the valence band and 0.3 eV for the conduction band, respectively, by ultraviolet photoelectron spectroscopy and electron-energy-loss spectroscopy. It is also observed that the valence-band structure of the GaS overlayer becomes much sharper after annealing.

ISSN:1071-1023    

DOI:10.1116/1.590251

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

We present data for a valved antimony cracker for use in solid-source molecular beam epitaxy. Both aspects of this source, the cracker and the valve, are characterized. In particular, the valve is shown to exhibit excellent performance in terms of control and reproducibility. As a demonstration of the capabilities of this source, continuously graded layers from GaAs to GaSb were grown by using the source in conjunction with a valved arsenic cracker. We discuss the influence of this source and other growth parameters on composition, structure, and morphology of these graded layers.

ISSN:1071-1023    

DOI:10.1116/1.590252

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The kinetics of GaAs nitridation usingN2plasmas, both radio frequency and electron cyclotron resonance sources, is investigated usingin situand real time ellipsometry. A comparison of plasma nitridation with the more conventionalNH3thermal nitridation of GaAs is also reported. We report that all the GaAs nitridation processes are self-limiting yielding only very thin GaN layers. The dependence of GaN layer thickness on surface pretreatment, surface temperature and N atom density in the plasma is reported. Smooth and stoichiometric GaN layers are formed atT<600 °C,whereas nitridation atT⩾600 °Cyields rough and Ga-rich GaN layers. In both cases, it is shown that As segregates at the GaAs/GaN interface, indicating that GaAs plasma nitridation kinetics is limited by outdiffusion of As and/or AsN species.

ISSN:1071-1023    

DOI:10.1116/1.590253

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The thermal decomposition of bulk and heteroepitaxial (100) InP surfaces is studied byin situscanning electron microscopy combined with mass spectrometry. The onset of P evaporation coincides with the In droplet nucleation at about 480 °C and the major evaporation of phosphorous commences above 510 °C and corresponds to the serious deterioration of the surface. There is no significant difference between bulk and defected (heteroepitaxial InP/GaAs) samples. The relevance to InP technology is discussed.

ISSN:1071-1023    

DOI:10.1116/1.590254

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The etching characteristics of GaAs andAl0.22Ga0.78Asin citric acid/hydrogen peroxide/ammonium hydroxide etching solution were studied. The selectivity of GaAs toAl0.22Ga0.78Aswas as high as 200 at20 °C(510 at0 °C) by optimizing thepHand citric acid/hydrogen peroxide ratio. To our knowledge, this is the best result. The etch rate of GaAs is 1000 Å/min and permits a good control of the etched depth. The effects of the etching solution temperature and the doping level of GaAs on the selectivity were determined. The solution stability study over the time proves that the process is very reliable. This wet etching was applied to the gate recess etching of a heterojunction field effect transistor (HFET). Observations and measurements by electron beam microscopy are presented for short gate lengths. They show a very good surface morphology and that the gate recess width is independent of the gate length. It only depends on the etching time. The breakdown voltage value can be adjusted by the gate recess width. The possibilities of this wet etching are consequently demonstrated to be particularly appropriate to the realization of millimeter power HFETs.

ISSN:1071-1023    

DOI:10.1116/1.590255

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

GaAs (100) surfaces were etched in citric acid-hydrogen peroxide(C6H8O7:H2O2)solutions with volume ratios ranging from 1:1 to 10:1.Ex situvariable angle spectroscopic ellipsometry measurements (1.5–5.5 eV) were made before and after etching for periods of up to 8 min. Analysis of these data indicated that low volume ratios (⩽2:1), with corresponding low etch rates, produced a thin interfacial layer (which might represent microscopic roughness) beneath a porous oxide. For a 1:1 ratio the interfacial layer thickness increased with etch time, while for a 2:1 ratio it stabilized at a small value (≅2 nm). Higher volume ratios (⩾3:1), associated with much higher etch rates, produced qualitatively different overlayers which were more absorbing and 4–6 nm thick. Their optical constants could be modeled as a mixture of a small fraction (typically 5%–10%) of crystalline arsenic in a low-dielectric medium, using an effective medium approximation. Similar effects were seen in etchedAl0.3Ga0.7Assurfaces. Low etch rates (volume ratio of 5:1 or less) resulted in nearly normal oxide overlayers. A high etch rate (volume ratio 10:1) resulted in an absorbing layer similar to the one seen on rapidly etched GaAs surfaces, 8–12 nm thick.

ISSN:1071-1023    

DOI:10.1116/1.590256

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Using electron beam evaporation, aSi/CeO2/Si(111) structure has been grown in a molecular beam epitaxy machine.In situlow energy electron diffraction, cross sectional transmission electron microscopy, selected area diffraction, and atomic force microscopy have been used to structurally characterize the overlying silicon layer and show it to be single crystalline and epitaxially oriented. Rutherford backscattering and energy dispersive x-ray analysis have been used to confirm the presence of a continuous 23 ÅCeO2layer at the interface. Rutherford backscattering and x-ray photoemission spectroscopy show an additional presence of cerium both at the exposed silicon surface and incorporated in low levels(∼1%)within the silicon film, suggesting a growth mechanism with cerium riding atop the silicon growth front leaving behind small amounts of cerium incorporated in the growing silicon crystal.

ISSN:1071-1023    

DOI:10.1116/1.590257

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Inductively coupled plasma etching of InGaP, AlInP and AlGaP inBI3orBBr3discharges was investigated as a function of source power, dc chuck bias and plasma composition. InGaP etches at the fastest rates(>6000 Å min−1)in both chemistries, followed by AlGaP. It is found that AlInP provides an excellent etch stop for the other two materials in both mixtures. The InGaP surface morphology improves with increasingBI3orBBr3content, and with increasing dc chuck bias. The etched features for this material are highly anisotropic. Etch selectivities for InGaP overSiO2andSiNxof⩾8are obtained in both plasma chemistries, and there is no etch incubation time with either mixture, indicating that both can scavenge the native oxide on InGaP, AlGaP and AlInP.

ISSN:1071-1023    

DOI:10.1116/1.590258

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

A dry etching process is described for the fabrication of through-wafer via holes in GaAs-based monolithic microwave integrated circuits by magnetron ion etching usingSiCl4.The process has been used to etch via holes through 80 μm GaAs substrates with good anisotropy and etch rates exceeding 1 μm/min for via holes as small as 18×20μm2. Etch anisotropy appears to be due to an etch-inhibiting layer, which forms on the sidewalls but can be removed readily using a briefSF6/O2etch. The process also exhibits good selectivity to Au and Ni frontside metal.

ISSN:1071-1023    

DOI:10.1116/1.590259

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Sub-half-micron device design rules require precise control over two critical etch layers: transistor polysilicon gate definition and contact formation. The definition of the transistor polysilicon gate electrode is essential to the performance of the device. In addition, the small geometries and thin underlying gate oxide demand a high level of control over the gate dimensions. The design rules also require the formation of high-aspect-ratio contacts and vias with nearly vertical sidewalls and minimal critical dimension variation. To define these features, a deep-ultraviolet photolithography process was developed, incorporating a bottom antireflective coating (ARC). The etch processes used to translate these features into polysilicon (gates) and oxide (contacts) required anin situARC dry–develop step and a fast etch rate for high throughput with good uniformity while maintaining a high selectivity to any underlying layers. To achieve these stringent requirements, low-pressure, high-density-plasma reactors with independent substrate bias power control were needed.

ISSN:1071-1023    

DOI:10.1116/1.590260

出版商:American Vacuum Society    

年代:1998

数据来源: AIP