Comparison of the effect of gate dielectric layer on 2DEG carrier concentration in strained AlGaN/GaN heterostructure

2004 ◽  
Vol 831 ◽  
Author(s):  
W. Wang ◽  
J. Derluyn ◽  
M. Germain ◽  
I. Dewolf ◽  
M. Leys ◽  
...  
Keyword(s):  
Carrier Concentration ◽  
Layer Thickness ◽  
Surface Passivation ◽  
Gate Dielectric ◽  
Algan Layer ◽  
Polarization Model ◽  
Quantitative Results ◽  
Gan Heterostructure ◽  
Interesting Behavior

ABSTRACTThe effect of surface passivation on undoped AlGaN/GaN heterostructures using SiO2, Al2O3, Ta2O5 and Si3N4 as a function of layer thickness is presented. It is found that all of the oxides caused decreased 2DEG carrier concentration with increasing thickness of the respective oxide layers between the gate and AlGaN layer. On the contrary, the 2DEG carrier concentration increased strongly with increasing Si3N4 layer thickness. An elementary polarization model was used to fit the behavior for all materials and thicknesses leading to quantitative results. The fitting suggests that the effect of the oxides and Si3N4 on the 2DEG carrier concentration can be explained by the differences between them with respect to charge accumulation at the AlGaN/dielectric interface. High temperature in-situ deposited Si3N4 especially shows interesting behavior by bowing measurements as it also adds strain which increases piezoelectric polarization charge in AlGaN layer, so that increases the charge density in the 2DEG.

Investigation of In Situ SiN as Gate Dielectric and Surface Passivation for GaN MISHEMTs

2017 ◽  
Vol 64 (3) ◽  
pp. 832-839 ◽  
Author(s):  
Huaxing Jiang ◽  
Chao Liu ◽  
Yuying Chen ◽  
Xing Lu ◽  
Chak Wah Tang ◽  
...  
Keyword(s):  
Surface Passivation ◽  
Gate Dielectric

The Interface Properties of La2O3/GaAs System by Surface Passivation

2012 ◽  
Vol 557-559 ◽  
pp. 1815-1818 ◽  
Author(s):  
Ting Ting Jia ◽  
Xing Hong Cheng ◽  
Duo Cao ◽  
Da Wei Xu ◽  
You Wei Zhang ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Surface Passivation ◽  
Gate Dielectric ◽  
Surface Preparation ◽  
Atomic Layer ◽  
Native Oxide ◽  
Atomic Force ◽  
Transmission Electron ◽  
Layer Deposition

In this work, La2O3 gate dielectric film was deposited by plasma enhanced atomic layer deposition. we investigate the effect of surface preparation of GaAs substrate, for example, native oxide, S-passivation, and NH3 plasma in situ treatment. The interfacial reaction mechanisms of La2O3 on GaAs is studied by means of X-ray photoelectron spectroscopy(XPS), high-resolution transmission electron microscopy(HRTEM) and atomic force microscope (AFM). As-O bonding is found to get effectively suppressed in the sample GaAs structures with both S-passivation and NH3 plasma surface treatments.

Hydrostatic Pressure Studies of GaN/AlGaN/GaN Heterostructure Devices with Varying AlGaN Thickness and Composition

2007 ◽  
Vol 994 ◽  
Author(s):  
Isaiah Steinke ◽  
M. Z. Kauser ◽  
P. Paul Ruden ◽  
Xianfeng Ni ◽  
Hadis Morkoc ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Layer Thickness ◽  
Reverse Bias ◽  
Forward Bias ◽  
Pressure Gauge ◽  
Algan Layer ◽  
Turn On ◽  
Sensing Applications ◽  
Gan Heterostructure ◽  
Heterostructure Devices

AbstractGaN-based heterostructure devices are of interest for pressure and stress sensing applications due to their potential for use at high temperatures and in caustic environments. We have grown n-GaN/u-AlGaN/n-GaN heterostructure devices on sapphire substrates by organometallic vapor phase epitaxy (OMVPE) using the epitaxial layer overgrowth (ELO) method. The devices were fabricated with varying AlGaN layer thickness and composition. Current-voltage (I-V) characteristics were obtained to characterize the performance of these devices under hydrostatic pressures up to 500 MPa. For a fixed bias, the current was observed to decrease in magnitude with increasing hydrostatic pressure for all devices tested. The current modulation is attributed to piezoelectric effects. Specifically, the polarization charge densities at both GaN/AlGaN interfaces are sensitive to changes in the hydrostatic pressure, and these charges affect the shape of the potential barrier and the current. Changes in the AlGaN layer thickness and composition modify the interfacial polarization, with thicker AlGaN layers and higher Al content increasing the effect of pressure on the observed I-V characteristics. The decreases in current magnitude with increasing pressure are linear over the pressure range tested. In order to quantify the performance of these devices, we calculate a pressure gauge factor based on a normalized change in current divided by the change in pressure. Values obtained range from 0.1–1.0 GPa−1, consistent with our previously published results for a single device. In addition, the turn-on voltages under both forward and reverse bias conditions are observed to increase with increasing AlGaN layer thickness and composition, a result that agrees with our device model. These turn-on voltages are governed by different mechanisms in the forward and reverse bias directions. Under forward bias, the mechanism is a transition from a thermionic to a tunneling process. However, under reverse bias, the turn-on occurs when the total electric field changes sign in the AlGaN layer.

Exciton dynamics in thick GaN MOVPE epilayers deposited on sapphire.

1997 ◽  
Vol 2 ◽  
Author(s):  
J. Allègre ◽  
P. Lefebvre ◽  
J. Camassel ◽  
B. Beaumont ◽  
Pierre Gibart
Keyword(s):  
Layer Thickness ◽  
Buffer Layers ◽  
Rate Equations ◽  
Time Resolved ◽  
Versus Layer ◽  
Level Model ◽  
Shallow Impurities ◽  
Aln Buffer ◽  
Time Resolved Photoluminescence

Time-resolved photoluminescence spectra have been recorded on three GaN epitaxial layers of thickness 2.5 μm, 7 μm and 16 μm, at various temperatures ranging from 8K to 300K. The layers were deposited by MOVPE on (0001) sapphire substrates with standard AlN buffer layers. To achieve good homogeneities, the growth was in-situ monitored by laser reflectometry. All GaN layers showed sharp excitonic peaks in cw PL and three excitonic contributions were seen by reflectivity. The recombination dynamics of excitons depends strongly upon the layer thickness. For the thinnest layer, exponential decays with τ ~ 35 ps have been measured for both XA and XB free excitons. For the thickest layer, the decay becomes biexponential with τ1 ~ 80 ps and τ2 ~ 250 ps. These values are preserved up to room temperature. By solving coupled rate equations in a four-level model, this evolution is interpreted in terms of the reduction of density of both shallow impurities and deep traps, versus layer thickness, roughly following a L−1 law.

Surface Passivation of Bare Aluminum Nanoparticles using Perfluoroalkyl Carboxylic Acids

2003 ◽  
Vol 800 ◽  
Author(s):  
R. Jason Jouet ◽  
Andrea D. Warren ◽  
David M. Rosenberg ◽  
Victor J. Bellitto
Keyword(s):  
Composite Material ◽  
Surface Passivation ◽  
Catalytic Decomposition ◽  
Self Assembled Monolayers ◽  
Aluminum Nanoparticles ◽  
Wet Chemistry ◽  
Al Nanoparticles ◽  
Polar Organic Solvents ◽  
Assembled Monolayers

AbstractSurface passivation of unpassivated Al nanoparticles has been realized using self assembled monolayers (SAMs). Nanoscale Al particles were prepared in solution by catalytic decomposition of H3Al•NMe3 or H3Al•N(Me)Pyr by Ti(OiPr)4 and coated in situ using a perfluoroalkyl carboxylic acid SAM. Because the Al particles are prepared using wet chemistry techniques and coated in solution, they are free of oxygen passivation. This SAM coating passivates the aluminum and seems to prevent the oxidation of the particles in air and renders the composite material, to some extent, soluble in polar organic solvents such as diethyl ether. Characterization data including SEM, TEM, TGA, and ATR-FTIR of prepared materials is presented.

Material Reliability of Low-Temperature Boron Deposition for PureB Silicon Photodiode Fabrication

MRS Advances ◽  
2018 ◽  
Vol 3 (57-58) ◽  
pp. 3397-3402 ◽  
Author(s):  
L.K. Nanver ◽  
K. Lyon ◽  
X. Liu ◽  
J. Italiano ◽  
J. Huffman
Keyword(s):  
High Temperature ◽  
Layer Thickness ◽  
Vapor Deposition ◽  
Dark Current ◽  
Deposition Temperature ◽  
Chemical Vapor ◽  
Silicon Photodiode ◽  
In Situ Methods ◽  
Deposition Conditions

ABSTRACTThe chemical-vapor deposition conditions for the growth of pure boron (PureB) layers on silicon at temperatures as low as 400°C were investigated with the purpose of optimizing photodiodes fabricated with PureB anodes for minimal B-layer thickness, low dark current and chemical robustness. The B-deposition is performed in a commercially-available Si epitaxial reactor from a diborane precursor. In-situ methods commonly used to improve the cleanliness of the Si surface before deposition are tested for a deposition temperature of 450°C and PureB layer thickness of 3 nm. Specifically, high-temperature baking in hydrogen, and exposure to HCl are tested. Both material analysis and electrical diode characterization indicate that these extra cleaning steps degrade the properties of the PureB layer and the fabricated diodes.

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