Gadolinium Oxide Gate Dielectrics for GaN MOSFETs

2001 ◽  
Vol 680 ◽  
Author(s):  
B.P. Gila ◽  
J.W. Johnson ◽  
K. N. Lee ◽  
V. Krishnamoorthy ◽  
S. Bates ◽  
...  
Keyword(s):  
Single Crystal ◽  
Oxide Films ◽  
Gadolinium Oxide ◽  
Ex Situ ◽  
Native Oxide ◽  
Breakdown Field ◽  
Thermally Stable ◽  
Amorphous Films ◽  
Substrate Temperatures

ABSTRACTSubstrate preparation of GaN, both in-situ and ex-situ, and the growth of gadolinium oxide, Gd2O3, by Gas source molecular beam epitaxy (GSMBE) have been investigated. Ex-situ cleaning techniques included wet chemical etching and UV-ozone treatments to remove surface contaminants and the native oxide. In-situ cleaning consisted of thermal treatment with and without exposure to an electron cyclotron resonance (ECR) oxygen plasma. A GaN (1x3) streaky RHEED pattern was the final product of this surface treatment study. Various growth initiation techniques were explored to produce Gd2O3 films with different microstructures as evidenced by RHEED, TEM, and XRD. Gd2O3 films planarized the initial GaN surface and stoichiometry was maintained over a range of substrate temperatures (300° to 650°C). Single crystal gadolinium oxide films were grown at substrate temperatures of 600-650°C. These films exhibited a breakdown field strength (EBD) of ∼1MV/cm, and showed high leakage current at high forward bias due to defects within the oxide. Single crystal oxide films were found to be thermally stable at annealing temperatures up to 1000°C. Quasi-amorphous films were grown at a substrate temperature of 100°C. These films exhibited a higher E BD of ∼3MV/cm and an interface state density of 3 × 1011 cm−2eV−1. However, the quasi-amorphous films were not thermally stable at 1000°C, showing evidence of re-crystallization in x-ray diffraction (XRD) scans.

On The Optimized Nucleation of Near-Single-Crystal Cvd Diamond Film

1995 ◽  
Vol 416 ◽  
Author(s):  
L. C. Chen ◽  
C. C. Juan ◽  
J. Y. Wu ◽  
K. H. Chen ◽  
J. W. Teng
Keyword(s):  
Single Crystal ◽  
Photoelectron Spectroscopy ◽  
Morphological Evolution ◽  
Present Report ◽  
Ex Situ ◽  
Nucleation Density ◽  
Induced Current ◽  
Current Time ◽  
Single Crystal Diamond

ABSTRACTNear-single-crystal diamond films have been obtained in a number of laboratories recently. The optimization of nucleation density by using a bias-enhanced nucleation (BEN) method is believed to be a critical step. However, the condition of optimized nucleation has never been clearly delineated. In the present report, a novel quantitative technique was established to monitor the nucleation of diamond in-situ. Specifically, the induced current was measured as a function of nucleation time during BEN. The timedependence of induced current was studied under various methane concentrations as well as substrate temperatures. The optimized nucleation condition can be unambiguously determined from the current-time plot. Besides the in-situ current probe, ex-situ x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were also used to investigate the chemical and morphological evolution. Characteristic XPS and AFM features of optimized nucleation is discussed.

In-situ and ex-situ characterization of surface oxide films on AB5-type metal hydride electrodes

1999 ◽  
Vol 293-295 ◽  
pp. 747-750 ◽  
Author(s):  
J.M Nan ◽  
Y Yang ◽  
J.K You ◽  
X.Q Li ◽  
Z.G Lin
Keyword(s):  
Metal Hydride ◽  
Oxide Films ◽  
Surface Oxide ◽  
Ex Situ ◽  
Metal Hydride Electrodes

Influence of Growth Parameters and Annealing on Properties of MBE Grown GaAsSbN SQWs

2005 ◽  
Vol 872 ◽  
Author(s):  
Liangjin Wu ◽  
Shanthi Iyer ◽  
Kalyan Nunna ◽  
Sudhakar Bharatan ◽  
Jia Li ◽  
...  
Keyword(s):  
Optical Properties ◽  
Substrate Temperature ◽  
Temperature Dependence ◽  
Growth Parameters ◽  
Blue Shift ◽  
Growth Conditions ◽  
Ex Situ ◽  
Single Quantum Well ◽  
Substrate Temperatures

AbstractIn this paper we report the growth of GaAsSbN/GaAs single quantum well (SQW) heterostructures by molecular beam epitaxy (MBE) and their properties. A systematic study has been carried out to determine the effect of growth conditions, such as the source shutter opening sequence and substrate temperature, on the structural and optical properties of the layers. The substrate temperatures in the range of 450-470 °C were found to be optimal. Simultaneous opening of the source shutters (SS) resulted in N incorporation almost independent of substrate temperature and Sb incorporation higher at lower substrate temperatures.The effects of ex-situ annealing in nitrogen ambient and in-situ annealing under As overpressure on the optical properties of the layers have also been investigated. A significant increase in photoluminescence (PL) intensity with reduced full width at half maxima (FWHM) in conjunction with a blue shift in the emission energy was observed on annealing the samples. In in-situ annealed samples, the PL line shapes were more symmetric and the temperature dependence of the PL peak energy indicated significant decrease in the exciton localization energy as exhibited by a less pronounced “S-shaped curve”. The “inverted S-shaped curve” observed in the temperature dependence of PL FWHM is also discussed. 1.61 μm emission with FWHM of 25 meV at 20K has been obtained in in-situ annealed GaAsSbN/GaAs SQW grown at 470 °C by SS.

Influence of Substrate Temperature During Sputter Deposition on the Subsequent Formation of Titanium Disilicide

2002 ◽  
Vol 745 ◽  
Author(s):  
A. S. Özcan ◽  
K. F. Ludwig ◽  
C. Cabral ◽  
C. Lavoie ◽  
J. M. E. Harper
Keyword(s):  
Substrate Temperature ◽  
Pole Figure ◽  
Texture Evolution ◽  
Sputter Deposition ◽  
Ex Situ ◽  
Phase Transformation Temperature ◽  
Subsequent Formation ◽  
X Ray ◽  
Substrate Temperatures

ABSTRACTWe examine how the substrate temperature during Ti film sputter deposition influences the subsequent texture formation in TiSi2 thin films. Titanium films of 32 nm thickness were sputtered onto Si(001) at elevated substrate temperatures varying between 100 °C and 900 °C. After the depositions, in situ x-ray diffraction (XRD) measurements were performed to study the thin film reactions in real time, as the samples were annealed. The XRD results show that the substrate temperature significantly influences the texture of the initial Ti film as well as the texture of the resulting C54-phase TiSi2. The preferred Ti orientation gradually changes from (002) to (101) fiber texture as the deposition temperature increases up to 500 °C. Films deposited at 600 °C transformed into the C49 phase during deposition while films deposited at 700 °C and higher temperatures transformed into the C54 phase during deposition. The series of deposited films was annealed up to 1000 °C in He to complete the C54 phase formation while monitoring the texture evolution in situ using a position sensitive x-ray detector. The XRD results show that the final C54 phase texture changes from a dominant (311) orientation normal to the substrate to a (010) orientation for substrate temperatures between 600 °C and 700 °C. The C49-C54 phase transformation temperature is also lowered for these deposition temperatures. Ex situ pole figure analysis of the film deposited at 700 °C confirms the dominant C54 (010) texture and shows an in-plane orientation with C54 [001] ∥ Si [110]. For substrate temperatures between 800 °C and 900 °C, the C54 texture changes dramatically. In this case, θ - 2 θ scans do not show a preferred C54 orientation, but pole figure analysis indicates weak inplane orientations.

TEM studies of spots crystallized in amorphous films by electron beam

1992 ◽  
Vol 50 (2) ◽  
pp. 1348-1349
Author(s):  
V. Yu. Kolosov
Keyword(s):  
Electron Beam ◽  
Crystal Growth ◽  
Single Crystal ◽  
Single Crystals ◽  
Central Zone ◽  
Lattice Orientation ◽  
Powerful Method ◽  
Amorphous Films ◽  
Explosive Crystallization

Electron beam (e-beam) annealing is powerful method for local modifying and crystallization in desired modes of semiconductors and microelectronics components and is also interesting for information storing. Nevertheless, discussed in many papers mechanism of explosive crystallization of amorphous (a-Ge, a-Si) films is still not clear enough and requires new structure studies. It is more relevant for recently discovered growing of micro-crystals with strong internal lattice bending (gradient crystals) in some amorphous films. This paper reports our findings in the structure of spots crystallized in these unusual modes by TEM beam in vacuum deposited (Ge, Se, Se-Te) or prepared by pyrolysis (Fe2O3) unsupported amorphous films. Bendcontour technique was used to analyze the fields of lattice orientation for gradient crystals, including in situ crystal growth studies or videorecord analysis.Explosively crystallized spots in a-Ge, a-Si films are known to consist of 3 zones, Fig. 1. We observed the same zones for films 400-800Å thick, deposited at rates 1- 100Å/s: polycrystal central zone (O), surrounded by a fan of radially elongated single crystals (zone R) which in turn is surrounded by zone (C), formed by concentric or spiral shells (each subdivided into single-crystal subshell and polycrystal subshell).

In-situ and ex-situ AFM imaging of μN load indents on silicate glass/alumina interfaces

1996 ◽  
Vol 54 ◽  
pp. 660-661
Author(s):  
A. V. Zagrebelny ◽  
E. T. Lilleodden ◽  
J. C. Nelson ◽  
S. Ramamurthy ◽  
C. B. Carter
Keyword(s):  
Single Crystal ◽  
Silicate Glass ◽  
Small Volume ◽  
Ex Situ ◽  
Surface Roughening ◽  
Mechanistic Approach ◽  
Afm Imaging ◽  
Indentation Analysis ◽  
Single Crystal Sapphire

Contact which only involves a small volume of material is becoming increasingly important to many industries including micromachines, microelectronics, and magnetic recording. The ability to characterize surface roughening on the micro- and nanoscopic scale is invaluable in understanding microplasticity due to indentation, scratches, wear, fatigue and epitactic mismatch. It has been demonstrated that AFM studies are appropriate for developing a mechanistic approach to μN load indentation analysis since they allow deformation volumes and residual depths to be measured and characterized directly and unambiguously.In the present study, interfaces between silicate glass and single-crystal α-Al2O3 have been studied using AFM and nanoindentation. The interfaces between the glass and the crystalline grains were prepared by growing films of anorthite (CaAl2Si2O8) composition with thickness ranging 100-200 nm on single-crystal sapphire substrates of {1120} (A-plane) and {1102} (R-plane) crystallographic orientations by pulsed-laser deposition (PLD). Some specimens were subjected to heat treatments in a conventional box furnace causing films to dewet the substrates. Fig. 1 shows schematically the morphology of the dewetted film which has resulted in the formation of distinctive islands, 0.5-2 μm in size. Both types of specimens were tested with two different micro/nanomechanical testers.

Characteristics of Ultra violet-Assisted Pulsed Laser Deposited Thin Oxide Films

2000 ◽  
Vol 623 ◽  
Author(s):  
V. Craciun ◽  
R.K. Singh
Keyword(s):  
Oxide Films ◽  
Pulsed Laser ◽  
Ultra Violet ◽  
Growth Conditions ◽  
Gaseous Species ◽  
Thin Oxide Films ◽  
Thin Oxide ◽  
Uv Photons ◽  
Substrate Temperatures

AbstractThe properties of thin oxide films such as Y2O3, ZnO and Ba0.5Sr0.5TiO3 grown using an in situ ultraviolet (UV)-assisted pulsed laser deposition (UVPLD) technique have been studied. With respect to films grown by conventional PLD under similar conditions but without UV illumination, the UVPLD grown films exhibited better structural and optical and electrical properties, especially for lower substrate temperatures. They also exhibited a better stoichiometry and contained less physisorbed oxygen than the conventional PLD grown layers. These improvements can be traced to several factors. Firstly, deep UV photons and ozone ensure a better in situ cleaning of the substrate prior to the deposition. Secondly, the presence of more reactive gaseous species like ozone and atomic oxygen formed by photodissociation of molecular O2 promotes the growth of more oxygenated films. Thirdly, absorption of UV photons by adatoms could result in an increased of their surface mobility. All these factors have a beneficial effect upon crystalline growth, especially for moderate substrate temperatures. For optimised growth conditions, the crystalline quality and properties of ultraviolet-assisted pulsed laser deposited films was similar to that of films grown using conventional PLD at substrate temperatures of at least 200°C higher.

In situ and ex situ characterisation of oxide films formed on strained stainless steel surfaces in high-temperature water

2006 ◽  
Vol 252 (24) ◽  
pp. 8580-8588 ◽  
Author(s):  
Yoichi Takeda ◽  
Tetsuo Shoji ◽  
Martin Bojinov ◽  
Petri Kinnunen ◽  
Timo Saario
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Oxide Films ◽  
Ex Situ ◽  
High Temperature Water ◽  
Steel Surfaces ◽  
Temperature Water

Ex situ and in situ determination of stress distributions in chromium oxide films by raman microscopy

1992 ◽  
Vol 33 (1) ◽  
pp. 1-12 ◽  
Author(s):  
J Birnie ◽  
C Craggs ◽  
D.J Gardiner ◽  
P.R Graves
Keyword(s):  
Chromium Oxide ◽  
Oxide Films ◽  
Raman Microscopy ◽  
Ex Situ ◽  
Stress Distributions

Native oxide free polycrystalline/single crystal Si interface obtained by in situ cleaning: effects on the electrical performances of polysilicon emitter transistors

1999 ◽  
Vol 43 (11) ◽  
pp. 2085-2091
Author(s):  
R.A. Puglisi ◽  
S.A. Lombardo ◽  
C. Spinella ◽  
S.U. Campisano ◽  
H. Monchoix ◽  
...  
Keyword(s):  
Single Crystal ◽  
Native Oxide ◽  
Polysilicon Emitter
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