Effect of RF Power on the Characteristic Parameters of W/n-GaAs Schottky Contacts Fabricated by RF Sputtering

1995 ◽  
Vol 378 ◽  
Author(s):  
A. Singh ◽  
G. Aroca ◽  
L. Velásquez
Keyword(s):  
Surface Defects ◽  
Defect Density ◽  
Forward Bias ◽  
Schottky Contact ◽  
Rf Sputtering ◽  
Low Frequency ◽  
Schottky Contacts ◽  
Rf Power ◽  
Order Of Magnitude ◽  
Density Surface

AbstractW/n-GaAs/In Schottky contacts of area 1.75 mm2 were fabricated by deposition of W on (100) n-GaAs by rf Sputtering using rf power values in the range 200–400 Watt. The I-V and high frequency C-V measurements at 300 K, in the 200 Watt W/n-GaAs Schottky contact indicated that W formed a good rectifying contact to n-GaAs, with a rectification ratio (r) of 270, ideality factor (n) of 1.39, reverse saturation current (Io) of 1.2×10−6 A and the C-V barrier height (φbo) of 1.6 V. However, n and Io increased, whereas r and φbo decreased for the W/n-GaAs Schottky contacts prepared using higher rf power. For the 300 Watt W/n-GaAs contact, the values of 70, 1.70, 6.3}10−6 A, and 1.2V for r, n, Io and φbo, respectively, were estimated. The low frequency forward bias capacitance (or surface defect density) was an order of magnitude higher in the 300 Watt contact than in the 200 Watt contact. This fact suggested that the degradation in the quality of W/n-GaAs Schottky contacts fabricated by using high rf power was caused by high density surface defects created during sputter deposition of W on n-GaAs.

Metastability Under High-Intensity Light of Device-Quality He-Diluted, H2-Diluted and Standard a-Si:H Films Deposited Between 50°C and 350°C

1994 ◽  
Vol 336 ◽  
Author(s):  
P. Morin ◽  
P. Roca i Cabarrocas
Keyword(s):  
High Intensity ◽  
Defect Density ◽  
Red Light ◽  
Rf Power ◽  
Wide Range ◽  
Order Of Magnitude ◽  
Kinetics Of ◽  
Defect Densities ◽  
High Intensity Light

ABSTRACTWe report the results of a study of the metastability under illumination by high intensity red light of device quality a-Si:H thin films deposited using a wide range of deposition conditions. The process variables included substrate temperature, pressure, rf power, and dilution of silane by He or H2. In-situ Monitoring of the sample conductivity and defect density during light-soaking provides the kinetics of the degradation of the electronic properties of the films. We observe equilibration of the photoconductivity and of the defect density. The characteristic time of equilibration τse of the defect density varies by more than an order of magnitude, dividing the samples into two groups: one group with a τse on the order of 103 seconds, the other with a τse on the order of 104 seconds. Low steady state defect densities combined with high ημτ products are observed for “standard” a-Si:H deposited between 100°C and 250°C and He-diluted films deposited above 250°C.

Admittance Measurements at Epitaxial and Nonepitaxial Silicide Schottky Contacts

1987 ◽  
Vol 91 ◽  
Author(s):  
J. Werner ◽  
R. T. Tung ◽  
A. F. J. Levi ◽  
M. Anzlowar
Keyword(s):  
Contact Resistance ◽  
Series Resistance ◽  
Schottky Contact ◽  
Low Frequency ◽  
Interface States ◽  
Extensive Study ◽  
Schottky Contacts ◽  
Imaginary Component ◽  
Minority Carriers

ABSTRACTWe report results of an extensive study examining the usefulness of low frequency capacitance measurements for the characterization of interface states at intimate Schottky contacts. Our measurements on epitaxial as well as on nonepitaxial silicides reveal that the imaginary component of the low frequency ac-admittance is usually inductive. This inductance is caused by minority carriers that are injected by the Schottky contact and modulate the conductivity of the series resistance of the bulk silicon. The frequently reported excess capacitances (instead of inductances) that were ascribed to interface states are only reproducible when we use imperfect back-contacts to the bulk Si that add a contact resistance to the equivalent dc-circuit of the Schottky diode. Excess low frequency capacitances at intimate Schottky contacts are therefore not related to interface states but rather to the contact resistance of the back-contact.

Effect of Doping on the Interface States in Au Schottky Contact to p-In0.21Ga0.79As Grown on GaAs by Metal Organic Vapour Phase Epitaxy

1993 ◽  
Vol 318 ◽  
Author(s):  
A. Singh ◽  
P. Cova ◽  
R. A. MASUT
Keyword(s):  
Doping Concentration ◽  
Schottky Diodes ◽  
Forward Bias ◽  
Schottky Contact ◽  
Frequency Dispersion ◽  
Vapour Phase ◽  
Interface State ◽  
Interface States ◽  
Vapour Phase Epitaxy ◽  
Order Of Magnitude

ABSTRACTEpitaxial p-In0.21Gao0.79As/Au Schottky barrier type diodes were fabricated by evaporation of Au on chemically etched surfaces of In0.21Ga0.79As:Zn layers grown on highly doped GaAs substrate by MOVPE. 1 MHz capacitance-voltage (C-V) and Capacitance-frequency (C-f) measurements were performed in the frequency range 1 KHz-1 MHz at room temperature in Au Schottky diodes made on four epitaxial In0.2 Ga0.79As:Zn samples with doping concentrations between 6×1014cm−3 and 4×1017 cm−3. Under forward bias, a large frequency dispersion in the junction capacitance was observed which was attributed to the interface states in thermal equilibrium with the semiconductor. The interface states capacitance extracted from the C-f data was analyzed in terms of Lehovec's theoretical model of interface state continuum with single time constant, and the characteristic parameters of the interface states (energy density (Nss), relaxation time (τ) and hole capture cross-section (σh)) were determined. In the samples with doping concentration in the range 1.5×1017-4.3×1017 cm−3, Nss was about an order of magnitude higher than in the sample having a doping concentration of 5.8×1014 cm−3. Over the interface states energy range 0.40-0.65 eV, Nss decreased exponentially with energy in the highly doped samples and σh increased with energy in all the samples.

Microstructure studies of tungsten silicide schottky contacts on Gaas

1987 ◽  
Vol 45 ◽  
pp. 328-329
Author(s):  
Yih-Cheng Shih ◽  
E. L. Wilkie
Keyword(s):  
Thermal Stability ◽  
Field Effect Transistors ◽  
Schottky Contact ◽  
Schottky Contacts ◽  
Excellent Thermal Stability ◽  
Barrier Heights ◽  
Gaas Substrates ◽  
Film Adhesion ◽  
Threshold Voltages ◽  
Thermal Stability Of

Tungsten silicides (WSix) have been successfully used as the gate materials in self-aligned GaAs metal-semiconductor-field- effect transistors (MESFET). Thermal stability of the WSix/GaAs Schottky contact is of major concern since the n+ implanted source/drain regions must be annealed at high temperatures (∼ 800°C). WSi0.6 was considered the best composition to achieve good device performance due to its low stress and excellent thermal stability of the WSix/GaAs interface. The film adhesion and the uniformity in barrier heights and ideality factors of the WSi0.6 films have been improved by depositing a thin layer of pure W as the first layer on GaAs prior to WSi0.6 deposition. Recently WSi0.1 has been used successfully as the gate material in 1x10 μm GaAs FET's on the GaAs substrates which were sputter-cleaned prior to deposition. These GaAs FET's exhibited uniform threshold voltages across a 51 mm wafer with good film adhesion after annealing at 800°C for 10 min.

A Study of Electron Beam Irradiation Influence on Device Contact Junction Characteristics of Advanced DRAM Using Atomic Force Probing

2013 ◽  
Author(s):  
Wei-Chih Wang ◽  
Jian-Shing Luo
Keyword(s):  
Electron Beam ◽  
Electron Beam Irradiation ◽  
Forward Bias ◽  
Irradiation Damage ◽  
Beam Irradiation ◽  
Excess Current ◽  
Atomic Force ◽  
Order Of Magnitude ◽  
Voltage Contrast ◽  
Acceleration Voltage

Abstract In this paper, we revealed p+/n-well and n+/p-well junction characteristic changes caused by electron beam (EB) irradiation. Most importantly, we found a device contact side junction characteristic is relatively sensitive to EB irradiation than its whole device characteristic; an order of magnitude excess current appears at low forward bias region after 1kV EB acceleration voltage irradiation (Vacc). Furthermore, these changes were well interpreted by our Monte Carlo simulation results, the Shockley-Read Hall (SRH) model and the Generation-Recombination (G-R) center trap theory. In addition, four essential examining items were suggested and proposed for EB irradiation damage origins investigation and evaluation. Finally, by taking advantage of the excess current phenomenon, a scanning electron microscope (SEM) passive voltage contrast (PVC) fault localization application at n-FET region was also demonstrated.

Study of 14.9 MeV Neutron Irradiation Effects on Ni/GaN Schottky Contacts Using Low‐Frequency Noise Spectroscopy

2019 ◽  
Vol 217 (7) ◽  
pp. 1900701
Author(s):  
Yuan Ren ◽  
Leidang Zhou ◽  
Kang Zhang ◽  
Liang Chen ◽  
Xiaoping Ouyang ◽  
...  
Keyword(s):  
Neutron Irradiation ◽  
Low Frequency ◽  
Schottky Contacts ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Irradiation Effects ◽  
Noise Spectroscopy

Investigations of Tail and Defect States in a-Si0.6Ge0.4:H Alloys by PDS and ESR - Implications for the Interaction of Weak and Dangling Bonds

1995 ◽  
Vol 377 ◽  
Author(s):  
Tilo P. Drüsedau ◽  
Andreas N. Panckow ◽  
Bernd Schröder
Keyword(s):  
Silicon Germanium ◽  
Defect Density ◽  
State Density ◽  
Model Parameters ◽  
Defect States ◽  
Conversion Model ◽  
Order Of Magnitude ◽  
Underlying Mechanisms ◽  
Amorphous Silicon Germanium ◽  
Excess Absorption

ABSTRACTInvestigations on the gap state density were performed on a variety of samples of hydrogenated amorphous silicon germanium alloys (Ge fraction around 40 at%) containing different amounts of hydrogen. From subgap absorption measurements the values of the “integrated excess absorption” and the “defect absorption” were determined. Using a calibration constant, which is well established for the determination of the defect density from the integrated excess absorption of a-Si:H and a-Ge:H, it was found that the defect density is underestimated by nearly one order of magnitude. The underlying mechanisms for this discrepancy are discussed. The calibration constants for the present alloys are determined to 8.3×1016 eV−1 cnr2 and 1.7×1016 cm−2 for the excess and defect absorption, respectively. The defect density of the films was found to depend on the Urbach energy according to the law derived from Stutzmann's dangling bond - weak bond conversion model for a-Si:H. However, the model parameters - the density of states at the onset of the exponential tails N*=27×1020 eV−1 cm−3 and the position of the demarcation energy Edb-E*=0.1 eV are considerably smaller than in a-Si:H.

GaInP Selective Area Epitaxy for Heterojunction Bipolar Transistor Applications

1996 ◽  
Vol 448 ◽  
Author(s):  
S. H. PARK ◽  
S.-L. FU ◽  
P. K. L. YU ◽  
P. M. ASBECK
Keyword(s):  
Light Field ◽  
Defect Density ◽  
Forward Bias ◽  
Dark Field ◽  
Bipolar Transistor ◽  
Heterojunction Bipolar Transistor ◽  
Current Gain ◽  
Selective Area Epitaxy ◽  
Metal Base ◽  
Selective Area

AbstractA study of selective area epitaxy (SAE) of GalnP lattice matched to GaAs is presented. The selectively regrown GaInP is used as the emitter of a novel heterojunction bipolar transistor (HBT) device structure. Successful SAE of GalnP on both dark field (mostly covered) and light field (mostly open) SiO2 masks is compared. To characterize the critical regrown heterojunction, diodes and HBTs were fabricated and measured. It is found that a pre-growth pause of either TEGa or PH3 results in forward bias characteristics with low leakage and an ideality factor of ~1.25, indicating low interfacial defect density. Non-self aligned regrown emitter HBTs grown with a dark field mask scheme have been fabricated. Devices with an emitter area of 3x12 μm exhibit small signal current gain up to 80 with an fT and fMAX of 22 GHz and 18 GHz, respectively. To further improve the performance of these devices, a structure with a self-aligned refractory metal base contact and light field regrowth is proposed.

Impurity and Stoichiometry Control in Atomic Layer Epitaxy

1992 ◽  
Vol 262 ◽  
Author(s):  
H. Yokoyama ◽  
K. Ikuta ◽  
N. Inoue
Keyword(s):  
Point Defects ◽  
Resonant Tunneling ◽  
Room Temperature ◽  
Defect Density ◽  
Atomic Layer ◽  
Negative Resistance ◽  
Atomic Layer Epitaxy ◽  
Tunneling Diode ◽  
Order Of Magnitude ◽  
Stoichiometry Control

ABSTRACTWe investigate the intrinsic point defects in epilayers grown by atomic layer epitaxy (ALE). Ga vacancies and antisite As atoms in the epilayers are detected by photoluminescence spectroscopy. This shows that the ALE epilayer was grown under As-rich conditions. We propose increasing the TMG flux to reduce the number of point defects. With this method, the number of point defects in ALE epilayers can be decreased to less than that in conventionally grown epilayers. Moreover, it is'found that these point defects are formed by the incomplete Ga coverage, not by the steric hindrance as previously suggested. The carbon concentration is decreased by one order of magnitude by using nitrogen instead of hydrogen as the carrier gas. As an application of this low defect density, we fabricated a GaAs/AlAs resonant tunneling diode and observed the negative resistance at room temperature.

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