Pt Schottky contacts on Ga- and N-face surfaces of free-standing GaN

2001 ◽  
Vol 680 ◽  
Author(s):  
U. Karrer ◽  
C.R. Miskys ◽  
O. Ambacher ◽  
M. Stutzmann
Keyword(s):  
Schottky Diodes ◽  
Reverse Current ◽  
Forward Direction ◽  
Hydride Vapor Phase Epitaxy ◽  
Free Standing ◽  
Band Bending ◽  
Barrier Heights ◽  
Consistent Solution ◽  
Lift Off ◽  
Gap States

ABSTRACTThick GaN films, grown by hydride vapor phase epitaxy (HVPE), were separated from their sapphire substrate with a laser-induced lift-off process. After cleaning and polishing, these films offer the most direct way to investigate and compare the influence of crystal polarity on the electronic properties of Ga-face and N-face surfaces, respectively. Different barrier heights for Pt Schottky diodes evaporated onto Ga- and N-face GaN are determined from the dependence of the effective barrier height versus ideality factor by I-V measurements to 1.15 eV and 0.80 eV, respectively. The charge neutrality condition at the surface is modified by the spontaneous polarization due to the polarization induced bound sheet charge. This effect has to be included in the electronegativity concept of metal induced gap states (MIGS) and can also be illustrated by different band bending of the conduction and valence band, inferred from the self-consistent solution of the Schrödinger-Poisson equation. Furthermore, temperature dependent I-V characteristics are compared to simulated behavior of Schottky diodes, exhibiting excellent agreement in forward direction, but showing deviations in the reverse current.

Passivation of Gaas by Novel P2S5/(NH4)2Sx Sulfurization Techniques

1992 ◽  
Vol 281 ◽  
Author(s):  
J. T. Hsieh ◽  
C. Y. Sun ◽  
H. L. Hwang
Keyword(s):  
Photoelectron Spectroscopy ◽  
Surface Passivation ◽  
Schottky Diodes ◽  
Lower Surface ◽  
State Density ◽  
Surface Band ◽  
Band Bending ◽  
Barrier Heights ◽  
Effective Barrier ◽  
Metal Work

ABSTRACTA new surface passivation technique using P2S5/(NH4)2S on GaAs was investigated, and the results are compared with those of the (NH4)2Sx treatment. With this new surface treatment, the effective barrier heights for both Al- and Au—GaAs Schottky diodes were found to vary with the metal work functions, which is a clear evidence of the lower surface state density. Results of I—V measurements show that P2S5/(NH4)2S—passivated diodes have lower reverse leakage current and higher effective barrier height than those of the (NH4)2Sx -treated ones. Auger Electron Spectroscopy, X—ray photoelectron spectroscopy and Raman scattering measurements were done to characterize the surfaces including their compositions and surface band bending. In this paper, interpretations on this novel passivation effect is also provided.

High Voltage Silicon Carbide Schottky Diodes with Single Zone Junction Termination Extension

2007 ◽  
Vol 556-557 ◽  
pp. 873-876 ◽  
Author(s):  
Konstantin Vassilevski ◽  
Irina P. Nikitina ◽  
Alton B. Horsfall ◽  
Nicolas G. Wright ◽  
Anthony G. O'Neill ◽  
...  
Keyword(s):  
High Voltage ◽  
Schottky Diodes ◽  
Reverse Current ◽  
Total Charge ◽  
Average Value ◽  
Barrier Heights ◽  
Device Processing ◽  
Additional Protection ◽  
Thick Layers ◽  
Contact Size

High voltage 4H-SiC Schottky diodes with single-zone junction termination extension (JTE) have been fabricated and characterised. Commercial 4H-SiC epitaxial wafers with 10, 20 and 45 +m thick n layers (with donor concentrations of 3×1015, 8×1014 and 8×1014 cm-3, respectively) were used. Boron implants annealed under argon flow at 1500°C for 30 minutes, without any additional protection of the SiC surface, were used to form JTE’s. After annealing, the total charge in the JTE was tuned by reactive ion etching. Diodes with molybdenum Schottky contacts exhibited maximum reverse voltages of 1.45, 3.3 and 6.7 kV, representing more than 80% of the ideal avalanche breakdown voltages and corresponding to a maximum parallel-plane electric field of 1.8 MV/cm. Diodes with a contact size of 1×1 mm were formed on 10 +m thick layers (production grade) using the same device processing. Characterisation of the diodes across a quarter of a 2-inch wafer gave an average value of 1.21 eV for barrier heights and 1.18 for ideality factors. The diodes exhibited blocking voltages (defined as the maximum voltage at which reverse current does not exceed 0.1 mA) higher than 1 kV with a yield of 21 %.

Quasi-Schottky Diodes on (n)In.53Ga.47as with Barrier Heights of 0.6 eV

1991 ◽  
Vol 240 ◽  
Author(s):  
M. Marso ◽  
P. Kordoš ◽  
R. Meyer ◽  
H. Lüth
Keyword(s):  
Schottky Barrier ◽  
Barrier Height ◽  
Schottky Diodes ◽  
Reverse Current ◽  
Surface Layers ◽  
Fully Depleted ◽  
Barrier Heights ◽  
Effective Barrier ◽  
Basic Parameters ◽  
And Control

ABSTRACTThe modification and control of the Schottky barrier height on (n)InGaAs is an important tool at the device preparation as the barrier height is very low, øB° = 0.2 eV. We report about the Schottky barrier enhancement on (n)InGaAs by thin fully depleted surface layers of high doped (p+)InGaAs. Structures with different thicknesses of (p+)InGaAs in the range from 8 to 80 nm were grown by LP MOVPE technique and quasi-Schottky diodes with different contact areas were prepared using titanium as a barrier metal. I-V and I-T characteristics were measured and analysed to obtain basic parameters of prepared diodes, i. e. ideality factor n, effective barrier height øB, series resistance Rgand reverse current density JR (1V). The barrier height enhancement increases with the thickness of the (p+)-layer. Effective barrier heights of øB>0.6 eV, i.e. higher than reported until now, can be obtained with the surface layers of (p+)InGaAs with thicknesses exceeding 25 nm.

scholarly journals Vertical GaN-on-GaN Schottky Diodes as α-Particle Radiation Sensors

Micromachines ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 519
Author(s):  
Abhinay Sandupatla ◽  
Subramaniam Arulkumaran ◽  
Ng Geok Ing ◽  
Shugo Nitta ◽  
John Kennedy ◽  
...  
Keyword(s):  
Collection Efficiency ◽  
Schottky Diodes ◽  
High Energy ◽  
Hydride Vapor Phase Epitaxy ◽  
Ultraviolet Rays ◽  
Charge Carrier Density ◽  
X Rays ◽  
Free Standing ◽  
Charge Collection Efficiency ◽  
Radiation Sensors

Among the different semiconductors, GaN provides advantages over Si, SiC and GaAs in radiation hardness, resulting in researchers exploring the development of GaN-based radiation sensors to be used in particle physics, astronomic and nuclear science applications. Several reports have demonstrated the usefulness of GaN as an α-particle detector. Work in developing GaN-based radiation sensors are still evolving and GaN sensors have successfully detected α-particles, neutrons, ultraviolet rays, x-rays, electrons and γ-rays. This review elaborates on the design of a good radiation detector along with the state-of-the-art α-particle detectors using GaN. Successful improvement in the growth of GaN drift layers (DL) with 2 order of magnitude lower in charge carrier density (CCD) (7.6 × 1014/cm3) on low threading dislocation density (3.1 × 106/cm2) hydride vapor phase epitaxy (HVPE) grown free-standing GaN substrate, which helped ~3 orders of magnitude lower reverse leakage current (IR) with 3-times increase of reverse breakdown voltages. The highest reverse breakdown voltage of −2400 V was also realized from Schottky barrier diodes (SBDs) on a free-standing GaN substrate with 30 μm DL. The formation of thick depletion width (DW) with low CCD resulted in improving high-energy (5.48 MeV) α-particle detection with the charge collection efficiency (CCE) of 62% even at lower bias voltages (−20 V). The detectors also detected 5.48 MeV α-particle with CCE of 100% from SBDs with 30-μm DL at −750 V.

Localized mid-gap-states limited reverse current of diamond Schottky diodes

2012 ◽  
Vol 111 (10) ◽  
pp. 104503 ◽  
Author(s):  
T. Teraji ◽  
M. Y. Liao ◽  
Y. Koide
Keyword(s):  
Schottky Diodes ◽  
Reverse Current ◽  
Gap States

scholarly journals Fabrication of 2-Inch Free-Standing GaN Substrate on Sapphire With a Combined Buffer Layer by HVPE

2021 ◽  
Vol 9 ◽  
Author(s):  
Nanliu Liu ◽  
Yongjing Jiang ◽  
Jian Xiao ◽  
Zhiwen Liang ◽  
Qi Wang ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Low Cost ◽  
Annealing Treatment ◽  
Chemical Vapor ◽  
Hydride Vapor Phase Epitaxy ◽  
Crystal Quality ◽  
Free Standing ◽  
Lift Off ◽  
Underlying Mechanisms ◽  
Physical And Chemical

Free-standing GaN substrates are urgently needed to fabricate high-power GaN-based devices. In this study, 2-inch free-standing GaN substrates with a thickness of ~250 μm were successfully fabricated on double-polished sapphire substrates, by taking advantage of a combined buffer layer using hydride vapor phase epitaxy (HVPE) and the laser lift-off technique. Such combined buffer layer intentionally introduced a thin AlN layer, using a mix of physical and chemical vapor deposition at a relatively low temperature, a 3-dimensional GaN interlayer grown under excess ambient H2, and a coalescent GaN layer. It was found that the cracks in the epitaxial GaN layer could be effectively suppressed due to the large size and orderly orientation of the AlN nucleus caused by pre-annealing treatment. With the addition of a 3D GaN interlayer, the crystal quality of the GaN epitaxial films was further improved. The 250-μm thick GaN film showed an improved crystalline quality. The full width at half-maximums for GaN (002) and GaN (102), respectively dropped from 245 and 412 to 123 and 151 arcsec, relative to those without the 3D GaN interlayer. The underlying mechanisms for the improvement of crystal quality were assessed. This method may provide a practical route for fabricating free-standing GaN substrates at low cost with HVPE.

scholarly journals Schottky diodes based on 4H-SiC epitaxial layers

2021 ◽  
Vol 2103 (1) ◽  
pp. 012235
Author(s):  
A M Strel’chuk ◽  
E V Kalinina
Keyword(s):  
Schottky Barrier ◽  
Barrier Height ◽  
Schottky Barrier Height ◽  
Alternative Explanation ◽  
Schottky Diodes ◽  
Reverse Current ◽  
Epitaxial Layers ◽  
Barrier Heights ◽  
Current Voltage ◽  
Significant Spread

Abstract Forward and reverse current-voltage (IV) characteristics of Cr-SiC (4H) Schottky diodes based on epitaxial layers with doping (1-3)· 1015 cm-3 were studied in the temperature range of 300-550 K. It is shown that in many cases the IV characteristics are close to ideal, but a significant spread of the forward IV characteristics of diodes manufactured in the same way on the same epitaxial layer was found, probably due to the spread of the Schottky barrier heights reaching 0.3 eV. Heating of the diode, as well as packaging, can also change the Schottky barrier height. An alternative explanation suggests the presence of a powerful shunt.

Increased effective barrier heights in Schottky diodes by molecular‐beam epitaxy of CoSi2and Ga‐doped Si on Si(111)

1988 ◽  
Vol 64 (8) ◽  
pp. 4082-4085 ◽  
Author(s):  
R. W. Fathauer ◽  
T. L. Lin ◽  
P. J. Grunthaner ◽  
P. O. Andersson ◽  
J. M. Iannelli ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Schottky Diodes ◽  
Barrier Heights ◽  
Effective Barrier

Process-Dependent Electronic Structure at Metallized GaAs Contacts

1992 ◽  
Vol 260 ◽  
Author(s):  
L. J. Brillson ◽  
I. M. Vitomirov ◽  
A. Raisanen ◽  
S. Chang ◽  
R. E. Viturro ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Chemical Interaction ◽  
Deep Level ◽  
Multiple Roles ◽  
Atomic Scale ◽  
Photoemission Spectroscopy ◽  
Band Bending ◽  
Barrier Heights ◽  
Barrier Formation ◽  
Thermally Driven

ABSTRACTThe influence of metallization and processing on Schottky barrier formation provides the basis for one of several fruitful approaches for controlling junction electronic properties. Interface cathodo-and photoluminescence measurements reveal that electrically-active deep levels form on GaAs(100) surfaces and metal interfaces which depend on thermally-driven surface stoichiometry and reconstruction, chemical interaction, as well as surface misorientation and bulk crystal quality. These interface states are discrete and occur at multiple gap energies which can account for observed band bending. Characteristic trends in such deep level emission with interface processing provide guides for optimizing interface electronic behavior. Correspondingly, photoemission and internal photoemission spectroscopy measurements indicate self-consistent changes in barrier heights which may be heterogeneous and attributable to interface chemical reactions observed on a monolayer scale. These results highlight the multiple roles of atomic-scale structure in forming macroscopic electronic properties of compound semiconductor-metal junctions.

Metal Contacts on a-GaN

1996 ◽  
Vol 1 ◽  
Author(s):  
T. U. Kampen ◽  
W. Mönch
Keyword(s):  
Tight Binding ◽  
Image Force ◽  
Schottky Contacts ◽  
Metal Contacts ◽  
Zero Bias ◽  
Barrier Heights ◽  
Current Voltage ◽  
Optical Dielectric Constant ◽  
Optical Dielectric ◽  
Gap States

The Schottky barrier heights of silver and lead contacts on n-type GaN (0001) epilayers were determined from current-voltage characteristics. The zero-bias barrier heights and the ideality factors were found to be linearly correlated. Similar observations were previously reported for metal contacts on Si (111) and GaAs (110) surfaces. The barrier heights of ideal Schottky contacts are characterized by image force lowering of the barrier only. This gives an ideality factor of 1.01. From our data we obtain barrier heights of 0.82 eV and 0.73eV for ideal Ag and Pb contacts on GaN, respectively. The metal-induced gap states (MIGS) model predicts the barrier heights of ideal Schottky contacts on a given semiconductor to be linearly correlated with the electronegativities of the metals. The two important parameters of this MIGS-and-electronegativity model are the charge neutrality level (CNL) of the MIGS and a slope parameter. The CNL may be calculated from the dielectric band gap and using the empirical tight-binding method. The slope parameters are given by the optical dielectric constant of the respective semiconductor. The predictions of the MIGS model for metal/GaN contacts are confirmed by the results presented here and by barrier heights previously reported by others for Au, Ti, Pt, and Pd contacts on GaN.

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