The Impact of Non-Ideal Ohmic Contacts on the Performance of High-Voltage SiC MPS Diodes

2019 ◽  
Vol 963 ◽  
pp. 553-557
Author(s):  
Yaren Huang ◽  
Jonas Buettner ◽  
Benedikt Lechner ◽  
Gerhard Wachutka
Keyword(s):  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Schottky Contact ◽  
Wide Band ◽  
Contact Model ◽  
Carrier Injection ◽  
Wide Band Gap ◽  
Tunneling Model ◽  
P Type ◽  
The Impact

The wide band gap of SiC semiconductor devices constitutes a serious challenge to build good Ohmic contacts on the surface of the p-type material. This is reflected in the numerical analysis of ”realistic” devices, where we have to cope with serious problems, such as a shifting threshold voltage, reduced forward conductivity, and no noticeable conductivity modulation by minority carrier injection from p+-emitters, in matching measured data with simulation results, as a consequence of the significant impact of non-ideal poor Ohmic contacts. In this work, we used a Schottky contact model together with a barrier tunneling model, instead of common ideal Ohmic contact model, to simulate the non-ideal Ohmic contact on SiC MPS diodes. Based on this approach, the I-V characteristics of real Ohmic contacts can be reproduced in high-fidelity simulations, providing us physical insight of the observed operational behavior.

Microstructure and Transport Properties in Alloyed Ohmic Contacts to P-Type SiC and GaN for Power Devices Applications

2012 ◽  
Vol 711 ◽  
pp. 203-207
Author(s):  
Fabrizio Roccaforte ◽  
Alessia Frazzetto ◽  
Giuseppe Greco ◽  
Raffaella Lo Nigro ◽  
Filippo Giannazzo ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Electrical Characterization ◽  
Surface Preparation ◽  
Wide Band ◽  
Wide Band Gap ◽  
Annealing Conditions ◽  
High Ionization ◽  
Metallic Compounds ◽  
P Type ◽  
The Impact

The formation of good Ohmic contacts to p-type silicon carbide (SiC) and gallium nitride (GaN) is an important physical and technological concern, because of the difficulty to find metals with low Schottky barriers to p-type wide band gap materials, and due to the high ionization energies of p-type dopant impurities. Typically, to overcome these issues, alloyed metallic compounds are used. In this work, the electrical properties of alloyed Ohmic contacts to p-type (Al-implanted) 4H-SiC and p-type (Mg-doped epilayers) GaN are presented and correlated with their microstructure. The impact of the surface preparation and annealing conditions are discussed, reporting the cases of Al/Ti contacts to p-SiC and Au/Ni contacts to p-GaN. The electrical characterization as a function of temperature allowed to define the dominant transport mechanism and to determine the barrier heights.

Investigation of Al-Ti Ohmic Contact to N-Type 4H-SiC

2012 ◽  
Vol 711 ◽  
pp. 184-187 ◽  
Author(s):  
Alexia Drevin-Bazin ◽  
Jean Francois Barbot ◽  
Thierry Cabioch ◽  
Marie France Beaufort
Keyword(s):  
Contact Resistance ◽  
Barrier Height ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Wide Band ◽  
Interfacial Structure ◽  
Max Phase ◽  
Specific Contact Resistance ◽  
Formation Mechanisms ◽  
P Type

Metal/semiconductor contacts have a great impact on device performances. Contact properties to wide band gap semiconductors, in particular, are more difficult to control due to the large potential barrier which arises when the metal is deposited on the semiconductor’s surface. Moreover, intrinsic interface states also lead to deviation of the Schottky-Mott limit and the barrier height is no more dependent of the work function of the metal. The contact property has also become very important with the race for miniaturisation toward the nanoscale. Contacts must also be adherent, able to resist to the temperatures for which SiC based-devices are intended, and also they should be compatible with conventional device processing techniques (die attachment). Ohmic contacts to SiC have thus been investigated for decades. The difficulties of controlling the interface properties between the metal and SiC to obtain low resistive ohmic contact have not been overcome yet; the specific contact resistance being proportional to the exponential of the barrier height for a given doping concentration. For example, nickel has been studied for the ohmic contacts on n and p-type, however the presence of voids at the interface has been reported leading to the degradation of the contact properties [1]. More recently low ohmic contact resistance has been reported of Au/Ti/Al/n-type-4H-SiC contact [2]. The formation of TiSi, TiSi2and Ti3SiC2has been reported according to x-ray diffraction experiments after annealing. The formation of Ti3SiC2(or MAX phase) has also been reported in TiAl-based contacts to both n-and p-type [3-6]. This ternary carbide layer is supposed to reduce the barrier height at the contact and thus leads to low contact resistances. The addition of Ge also leads to the formation of Ti3SiC2at lower temperature of annealing [7]. However, other compounds are frequently observed at the interface showing that the control of the interfacial structure must be optimized. The objective of our work is to obtain uniform epitaxial Ti3SiC2thin film on n-type 4H-SiC to form ohmic contact with low resistance by studying the influence of different parameters such as the role of Aluminium on the formation mechanisms, the polarity and doping dependence. The temperature and the annealing time are also parameters to be optimized for the improvement of the ohmic contact.

A TEM Study of Cr Based Contacts to (0001) 6H-SiC

2000 ◽  
Vol 6 (S2) ◽  
pp. 1064-1065
Author(s):  
R.-J. Liu ◽  
M. J. Kim ◽  
R. W. Carpenter ◽  
L. M. Porter ◽  
L. P. Scheunemann ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Optoelectronic Devices ◽  
Wide Band ◽  
Electron Beam Evaporation ◽  
Rapid Thermal Anneal ◽  
Wide Band Gap ◽  
Ohmic Behavior ◽  
Transmission Electron ◽  
P Type ◽  
Sic Films

6H-SiC is a wide band-gap semiconductor. In recent years, a variety of high-power, -temperature, -speed and optoelectronic devices have been produced in SiC films. The search for metals which can form thermally stable, uniform ohmic contacts with SiC with low resistivity is still ongoing. In this study, Cr and CrBx (1<x<2) films were deposited by electron beam evaporation onto p-type, vicinal Si-terminated (0001) 6H-SiC surface. Both contacts exhibited rectifying behavior in the as-deposited condition. Ohmic-like behavior was observed for Cr/SiC system after annealing at 1000 °C for 240 seconds in a rapid thermal anneal furnace in an Ar atmosphere. It was also reported that ohmic behavior was observed for CrB2 /SiC system after annealing at 1100 °C for 2 minutes at a pressure of 5x10“7 Torr.2 The microstructure and chemistry of these two contact systems in both as-deposited and annealed conditions were investigated by transmission electron microscopy (TEM).

Wide band gap and p-type conductive Cu-Nb-O films

2011 ◽  
Vol 5 (4) ◽  
pp. 153-155 ◽  
Author(s):  
Seiji Yamazoe ◽  
Shunsuke Yanagimoto ◽  
Takahiro Wada
Keyword(s):  
Band Gap ◽  
Wide Band ◽  
Wide Band Gap ◽  
P Type

A pathway to p-type wide-band-gap semiconductors

2009 ◽  
Vol 95 (17) ◽  
pp. 172109 ◽  
Author(s):  
Anderson Janotti ◽  
Eric Snow ◽  
Chris G. Van de Walle
Keyword(s):  
Band Gap ◽  
Wide Band ◽  
Wide Band Gap ◽  
Wide Band Gap Semiconductors ◽  
P Type

The Microstructure and Electrical Properties of Directly Deposited TiN Ohmic Contacts to Gallium Nitride.

1999 ◽  
Vol 595 ◽  
Author(s):  
P. Ruterana ◽  
G. Nouet ◽  
Th. Kehagias ◽  
Ph. Komninou ◽  
Th. Karakostas ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Electrical Properties ◽  
Film Thickness ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Epitaxial Relationship ◽  
Si Doped ◽  
P Type ◽  
20 Nm

AbstractWhen the stoichiometric TiN was deposited directly on GaN, we obtained columnar TiN grains of 5-20 nm section which cross the whole film thickness and are rotated mostly around the [111] axis. The conventional epitaxial relationship is obtained and no amorphous patches are observed at the interface. The deposition of TiN on Si doped GaN layers lead to the formation of an ohmic contact, whereas we obtain a rectifying contact on p type layers.

SiC vs. Si - Evaluation of Potentials for Performance Improvement of Power Electronics Converter Systems by SiC Power Semiconductors

2010 ◽  
Vol 645-648 ◽  
pp. 1101-1106 ◽  
Author(s):  
Jürgen Biela ◽  
Mario Schweizer ◽  
Stefan Waffler ◽  
Benjamin Wrzecionko ◽  
Johann Walter Kolar
Keyword(s):  
Band Gap ◽  
Power Electronics ◽  
Power Density ◽  
Performance Improvement ◽  
Wide Band ◽  
System Level ◽  
Wide Band Gap ◽  
Power Semiconductors ◽  
Power Electronics Converter ◽  
The Impact

Switching devices based on wide band gap materials as SiC oer a signicant perfor- mance improvement on the switch level compared to Si devices. A well known example are SiC diodes employed e.g. in PFC converters. In this paper, the impact on the system level perfor- mance, i.e. eciency/power density, of a PFC and of a DC-DC converter resulting with the new SiC devices is evaluated based on analytical optimisation procedures and prototype systems. There, normally-on JFETs by SiCED and normally-off JFETs by SemiSouth are considered.

scholarly journals A wide-band-gap p-type thermoelectric material based on quaternary chalcogenides of Cu2ZnSnQ4 (Q=S,Se)

2009 ◽  
Vol 94 (20) ◽  
pp. 202103 ◽  
Author(s):  
Min-Ling Liu ◽  
Fu-Qiang Huang ◽  
Li-Dong Chen ◽  
I-Wei Chen
Keyword(s):  
Band Gap ◽  
Thermoelectric Material ◽  
Wide Band ◽  
Wide Band Gap ◽  
P Type

scholarly journals GaN Based p-n Structures Grown on SiC Substrates

1996 ◽  
Vol 1 ◽  
Author(s):  
V.A. Dmitriev
Keyword(s):  
Band Gap ◽  
Bright Light ◽  
Wide Band ◽  
Injection Laser ◽  
Light Emitters ◽  
Wide Band Gap ◽  
High Quality ◽  
P Type

Wide band gap nitrides(InN, GaN, AlN) have been considered promising optoelectronics materials for many years [1]. Recently two main technological problems in the nitrides were overcome: (1)high quality layers has been grown on both sapphire and SiC substrates and(2) p-type GaN and AlGaN material has been obtained. These achievements resulted in the fabrication of bright light emitters in the violet, blue and green spectral regions [2].First injection laser has been demonstrated [3]. This paper reviews results obtained over the last few years on nitride p-n junctions, particularly on GaN based p-n junctions grown on SiC substrates. We will consider GaN p-n junctions, AlGaN p-n junctions, GaN and AlGaN p-i-n structures, and, finally, GaN/SiC p-n structures.

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