Electrical Characteristics of Schottky Contacts on Ge-Doped 4H-SiC

2014 ◽  
Vol 778-780 ◽  
pp. 706-709 ◽  
Author(s):  
Marilena Vivona ◽  
Kassem Al Assaad ◽  
Véronique Soulière ◽  
Filippo Giannazzo ◽  
Fabrizio Roccaforte ◽  
...  
Keyword(s):  
Schottky Barrier ◽  
Schottky Diodes ◽  
Sample Surface ◽  
Schottky Contacts ◽  
Electrical Characteristics ◽  
Conductive Atomic Force Microscopy ◽  
Near Surface ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After

We report on the electrical characteristics of Ni/4H-SiC Schottky contacts fabricated on a Ge-doped 4H-SiC epilayer. The morphology and the current mapping carried out by conductive atomic force microscopy on the epilayer allowed observing nanoscale preferential conductive paths on the sample surface. The electrical characteristics of Ni contacts have been studied before and after a rapid thermal annealing process. A highly inhomogeneous Schottky barrier was observed in as-deposited diodes, probably related to the surface electrical inhomogeneities of the 4H-SiC epilayer. A significant improvement of the Schottky diodes characteristics was achieved after annealing at 700°C, leading to the consumption of the near surface epilayer region by Ni/4H-SiC reaction. After this treatment, the temperature behavior of the ideality factor and Schottky barrier height was comparable to that observed on commercial 4H-SiC material.

Preliminary Study on the Effect of Micrometric Ge-Droplets on the Characteristics of Ni/4H-SiC Schottky Contacts

2015 ◽  
Vol 821-823 ◽  
pp. 424-427
Author(s):  
Marilena Vivona ◽  
Filippo Giannazzo ◽  
Kassem Alassaad ◽  
Véronique Soulière ◽  
Gabriel Ferro ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Schottky Barrier ◽  
Schottky Contacts ◽  
Electrical Characteristics ◽  
Conductive Atomic Force Microscopy ◽  
Double Barrier ◽  
Force Microscopy ◽  
Atomic Force ◽  
Current Conduction ◽  
Preliminary Study

This work reports on the morphological and electrical characteristics of Ni/4H-SiC Schottky contacts, fabricated on epitaxial layers intentionally covered by micrometric size Ge-droplets. Specifically, the Ge-droplets behave as preferential paths for the vertical current conduction, as observed at nanometric scale by conductive atomic force microscopy. As a consequence, the electrical I-V characteristics of these Ni contacts revealed the presence of a double-barrier, thus indicating an inhomogeneity in the interface. This behavior was associated to the local Schottky barrier lowering contribution due to the Ge-presence. These results can be useful to explore the possibility of controlling the contact (Schottky or Ohmic) properties by changing the size and the distribution of the surface impurities.

Investigation of Epitaxial GaN Films by Conductive Atomic Force Microscopy

2003 ◽  
Vol 764 ◽  
Author(s):  
S. Dogan ◽  
J. Spradlin ◽  
J. Xie ◽  
A. A. Pomarico ◽  
R. Cingolani ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Sample Surface ◽  
Conductive Atomic Force Microscopy ◽  
Force Microscopy ◽  
Topological Features ◽  
Atomic Force ◽  
Local Current ◽  
Semiconductor Junction ◽  
Surrounding Areas ◽  
Conduction Properties

AbstractThe current conduction in GaN is very topical and is the topic of a vast amount of research. By simultaneously mapping the topography and the current distribution, conductive atomic force microscopy (C-AFM) has the potential to establish a correlation between topological features and localized current paths. In this study, this technique was applied to image the conduction properties of as-grown and post-growth chemically etched samples GaN epitaxial layers on a microscopic scale. Our results show that prismatic planes have a significantly higher conductivity than the surrounding areas of the sample surface. A large and stable local current was mainly observed from the walls of the etched pits, under forward and reverse bias of the metallized AFM tip/semiconductor junction.

Two Dimensional Imaging of the Laterally Inhomogeneous Au/4H-SiC Schottky Barrier by Conductive Atomic Force Microscopy

2007 ◽  
Vol 556-557 ◽  
pp. 545-548 ◽  
Author(s):  
Filippo Giannazzo ◽  
Fabrizio Roccaforte ◽  
S.F. Liotta ◽  
Vito Raineri
Keyword(s):  
Atomic Force Microscopy ◽  
Schottky Barrier ◽  
Schottky Contact ◽  
Surface Preparation ◽  
Conductive Atomic Force Microscopy ◽  
Force Microscopy ◽  
Nano Scale ◽  
Atomic Force ◽  
Novel Approach ◽  
Inhomogeneous Character

We present a novel approach based on conductive atomic force microscopy (c-AFM) for nano-scale mapping of the Schottky barrier height (SBH) between a semiconductor and an ultrathin (1-5 nm) metal film. The method was applied to characterize the uniformity of the Au/4H-SiC Schottky contact, which is attractive for applications due to the high reported (∼1.8 eV) SBH value. Since this system is very sensitive to the SiC surface preparation, we investigated the effect on the nano-scale SBH distribution of a ∼2 nm thick not uniform SiO2 layer. The macroscopic I-V characteristics on Au/SiC and Au/not uniform SiO2/SiC diodes showed that the interfacial oxide lowers the average SBH. The c-AFM investigation is carried out collecting arrays of I-V curves for different tip positions on 1μm×1μm area. From these curves, 2D SBH maps are obtained with 10- 20 nm spatial resolution and energy resolution <0.1 eV. The laterally inhomogeneous character of the Au/SiC contact is demonstrated. In fact, a SBH distribution peaked at 1.8 eV and with tails from 1.6 eV to 2.1 eV is obtained. Moreover, in the presence of the not uniform oxide at the interface, the SBH distribution exhibits a 0.3 eV peak lowering and a broadening (tails from 1.1 eV to 2.1 eV).

The Effects of Kcn Etching on Cu-Rich Epitaxial CuInSe2 Thin Films

1996 ◽  
Vol 426 ◽  
Author(s):  
P. Fons ◽  
S. Nikl ◽  
A. Yamada ◽  
M. Nishitanp ◽  
T. Wada ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface Region ◽  
Etching Time ◽  
Cation Sublattice ◽  
Epitaxial Thin Films ◽  
Near Surface ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After ◽  
Integrated Intensity

AbstractA series of Cu-rich CuInSe2 epitaxial thin films were grown by molecular beam epitaxy on GaAs(001) substrates from elemental sources at a growth temperature of 450 °C. All samples were grown with an excess of Cu. Electron microprobe analysis (EPMA) indicated a Cu/ In ratio of about 2.1–2.6 in the as-grown films. Additionally, the Se/ (In+Cu) ratio was observed to be ∼0.95 indicating that the films were slightly Se poor. These Cu-rich samples were etched in a KCN solution for periods ranging from 30 seconds to 3 minutes. EPMA measurements indicated that the bulk Cu/ In ratio was reduced to ∼0.92 in all films regardless of etching time. Atomic force microscopy (AFM) was used to characterize the topology of each sample before and after etching. These measurements indicated that the precipitates present on the as-grown films were removed and large nearly isotropic holes were etched into the sample to a depth of over 1000 Å even for etching times as short as 30 seconds. The samples were also evaluated both before and after etching using a Phillips MRD diffractometer with parallel beam optics and a 18,000 watt Cu rotating anode X-ray source in the chalcopyrite [001], [101], and [112] directions. A peak was observed at ∼15 degrees in the [001] scan after etching consistant with the presence of the ordered vacancy compound, CuIn3Se5. Additionally the integrated intensity ratios of the chalcopyrite (202) reflection to the chalcopyrite (101) reflection ∝(fCu-fIn)2 along the [101] direction indicated the presence of a near-surface region containing cation sublattice disorder that was subsequently removed by the etching process.

scholarly journals Electrical Properties of Self-Assembled Nano-Schottky Diodes

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
F. Ruffino ◽  
A. Canino ◽  
M. G. Grimaldi ◽  
F. Giannazzo ◽  
F. Roccaforte ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Electrical Properties ◽  
Rutherford Backscattering Spectrometry ◽  
Schottky Diodes ◽  
Schottky Contact ◽  
Self Organization ◽  
Conductive Atomic Force Microscopy ◽  
Au Nanoclusters ◽  
Force Microscopy ◽  
Atomic Force

A bottom-up methodology to fabricate a nanostructured material by Au nanoclusters on 6H-SiC surface is illustrated. Furthermore, a methodology to control its structural properties by thermal-induced self-organization of the Au nanoclusters is demonstrated. To this aim, the self-organization kinetic mechanisms of Au nanoclusters on SiC surface were experimentally studied by scanning electron microscopy, atomic force microscopy, Rutherford backscattering spectrometry and theoretically modelled by a ripening process. The fabricated nanostructured materials were used to probe, by local conductive atomic force microscopy analyses, the electrical properties of nano-Schottky contact Au nanocluster/SiC. Strong efforts were dedicated to correlate the structural and electrical characteristics: the main observation was the Schottky barrier height dependence of the nano-Schottky contact on the cluster size. Such behavior was interpreted considering the physics of few electron quantum dots merged with the concepts of ballistic transport and thermoionic emission finding a satisfying agreement between the theoretical prediction and the experimental data. The fabricated Au nanocluster/SiC nanocontact is suggested as a prototype of nano-Schottky diode integrable in complex nanoelectronic circuits.

Characterization of Pt/a-Plane GaN Schottky Contacts Using Conductive Atomic Force Microscopy

2011 ◽  
Vol 11 (2) ◽  
pp. 1413-1416 ◽  
Author(s):  
Soo-Hyon Phark ◽  
Hogyoung Kim ◽  
Keun Man Song ◽  
Phil Geun Kang ◽  
Heung Soo Shin ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Schottky Contacts ◽  
Conductive Atomic Force Microscopy ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals Conductive Atomic Force Microscopy of Semiconducting Transition Metal Dichalcogenides and Heterostructures

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 803 ◽  
Author(s):  
Filippo Giannazzo ◽  
Emanuela Schilirò ◽  
Giuseppe Greco ◽  
Fabrizio Roccaforte
Keyword(s):  
Atomic Force Microscopy ◽  
Transition Metal ◽  
Grain Boundaries ◽  
Schottky Barrier ◽  
Transition Metal Dichalcogenides ◽  
Device Fabrication ◽  
Conductive Atomic Force Microscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Metal Dichalcogenides

Semiconducting transition metal dichalcogenides (TMDs) are promising materials for future electronic and optoelectronic applications. However, their electronic properties are strongly affected by peculiar nanoscale defects/inhomogeneities (point or complex defects, thickness fluctuations, grain boundaries, etc.), which are intrinsic of these materials or introduced during device fabrication processes. This paper reviews recent applications of conductive atomic force microscopy (C-AFM) to the investigation of nanoscale transport properties in TMDs, discussing the implications of the local phenomena in the overall behavior of TMD-based devices. Nanoscale resolution current spectroscopy and mapping by C-AFM provided information on the Schottky barrier uniformity and shed light on the mechanisms responsible for the Fermi level pinning commonly observed at metal/TMD interfaces. Methods for nanoscale tailoring of the Schottky barrier in MoS2 for the realization of ambipolar transistors are also illustrated. Experiments on local conductivity mapping in monolayer MoS2 grown by chemical vapor deposition (CVD) on SiO2 substrates are discussed, providing a direct evidence of the resistance associated to the grain boundaries (GBs) between MoS2 domains. Finally, C-AFM provided an insight into the current transport phenomena in TMD-based heterostructures, including lateral heterojunctions observed within MoxW1–xSe2 alloys, and vertical heterostructures made by van der Waals stacking of different TMDs (e.g., MoS2/WSe2) or by CVD growth of TMDs on bulk semiconductors.

Conductive Atomic Force Microscopy and Scanning Impedance Microscopy for the Imaging of Electrical Domain in CaCu3Ti4O12 Perovskite Oxide

2009 ◽  
Vol 1232 ◽  
Author(s):  
Raffaella Lo Nigro ◽  
Patrick Fiorenza ◽  
Vito Raineri
Keyword(s):  
Atomic Force Microscopy ◽  
Grain Boundaries ◽  
Electrical Characterization ◽  
Scanning Probe ◽  
Perovskite Oxide ◽  
Electrical Characteristics ◽  
Conductive Atomic Force Microscopy ◽  
Force Microscopy ◽  
Atomic Force

AbstractElectrical characterization of CaCu3Ti4O12 (CCTO) ceramics with scanning probe based techniques has been carried out. In particular, conductive atomic force microscopy (C-AFM) and scanning impedance microscopy (SIM) have been used to demonstrate the presence, shape and size in CCTO ceramics of the different electrically domains, both at the grain boundaries and within the grains. The electrical characteristics of single grains and of single domains have been evaluated and it has been observed that the conductive grains are surrounded by insulating grain boundaries.

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