Experimental and Physics-Based Study of the Schottky Barrier Height Inhomogeneity and Associated Traps Affecting 3C-SiC-on-Si Schottky Barrier Diodes (original) (raw)

A Defects’-based model on the Barrier Height behaviour in 3C-SiC-on-Si Schottky Barrier Diodes

IEEE Journal of Emerging and Selected Topics in Power Electronics

3C-Silicon Carbide (3C-SiC) Schottky Barrier Diodes on Silicon (Si) substrates (3C-SiC-on-Si) have been found to suffer of excessive sub-threshold current, despite the superior electrical properties of 3C-SiC. In turn, that is one of the factors deterring the commercialization of this technology. The forward Current-Voltage (I-V) characteristics in these devices carry considerable information about the material quality. In this context, an advanced Technology Computer Aided Design (TCAD) model is proposed and validated with measurements obtained from a fabricated and characterized Platinum/3C-SiCon-Si Schottky Barrier Diode with scope to shed light in the physical carrier transport mechanisms, the impact of traps and their characteristics on the actual device performance. The model includes defects originating from both the Schottky contact and the hetero-interface of 3C-SiC with Si, which allows the investigation of their impact on the magnification of the subthreshold current. Further, the simulation results and measured data allowed for the identification of additional distributions of interfacial states, the effect of which is linked to the observed nonuniformities of the Barrier Height value. A comprehensive characterization of the defects affecting the carrier transport mechanisms of the investigated 3C-SiC-on-Si power diode is thus achieved and the proposed TCAD model is able to accurately predict the device current both during forward and reverse bias conditions.

Barrier height inhomogeneities on Pd/n-4H-SiC Schottky diodes in a wide temperature range

Materials Science and Engineering: B, 2019

Barrier height inhomogeneities on Pd/n-type 4H-SiC Schottky barrier diodes in the 300-800 K temperature range have been investigated. Palladium is known to form silicide above 673 K. Temperature dependent currentvoltage (I-V) characteristics were analyzed. Barrier height (BH) and ideality factor (n) were found to be strongly temperature dependent. Barrier height increased, whilst ideality factor decreased with increasing in temperature and the Richardson plot showed some deviation from linearity. This was attributed to barrier inhomogeneities at the metal-semiconductor interface which resulted in a distribution of barrier heights. From the modified Richardson plot, the modified Richardson constant, A** was found to be 155 Acm −2 K −2 and 87 Acm-2 K −2 in the 300-525 K and the 550-800 K temperature ranges respectively.

Barrier height homogeneity for 4.5 kV 4H-SiC Schottky diodes

Superlattices and Microstructures, 2006

4.5 kV SiC Schottky diodes have been fabricated using Ni as the Schottky contact. A manufacturing yield of 40% is reached for the bigger area diodes (1.6 × 1.6 mm 2 ) and of 70% for the smaller ones (0.4 × 0.4 mm 2 ). The measured variations of barrier height and ideality factor with temperature do not agree with the thermionic model. This has been interpreted in terms of barrier height inhomogeneities using the Werner model. We extracted an average barrier height φ b = 1 eV and its standard deviation (σ = 90 mV). These two parameters are almost independent of the diode size. The variation of the barrier height distribution with field has also been investigated and shows a dependence similar to that of Schottky diodes realized from other semiconductor materials.

Barrier inhomogeneities of tungsten Schottky diodes on 4H-SiC

Semiconductor Science and Technology, 2008

Electrical properties of tungsten on silicon carbide (4H-SiC) Schottky diodes are investigated through the analysis of the forward current-voltage (I-V) characteristics measured at elevated temperatures within the range of 303-448 K. The subsequently derived Schottky barrier heights (SBHs) and ideality factors are found to be temperature dependent with distributions that are adequately explained within the framework of the model proposed by Tung in which he considers the barrier at a metal-semiconductor interface as consisting of locally non-uniform but interacting patches of different barrier heights embedded in a background of uniform barrier height. A uniform barrier height of 1.248 eV, a Richardson's constant of 129.95 A cm −2 K 2 and a factor T o of 23.92 K obtained agree very well with values published previously for similar Schottky barrier systems. Therefore, it has been concluded that the temperature-dependent I-V characteristics of the device can be successfully explained with lateral inhomogeneities distribution of the SBH.

Investigation of barrier inhomogeneities in Mo/4H–SiC Schottky diodes

Microelectronic Engineering, 2011

Using current-voltage measurements, we have investigated the electrical behavior of molybdenum on 4H-SiC Schottky diodes of various areas and having different edge terminations consisting of high resistivity guard rings manufactured by carbon ion-implantation.

Electrically active defects in SiC Schottky barrier diodes

The electrical properties of deep-level defects in real packaged SiC Schottky barrier rectifiers were studied by deep level transient spectroscopy (DLTS). One deep-level trap with an activation energy in the 0.29–0.30 eV range was revealed to be present in all the tested samples. The electrical characteristics of the trap indicate it is probably attributed to dislocations or to metastable defects, which can be responsible for discrepancies observed in I-V characteristics (see Ref. [2]). KeywordsSiC–Schottky diode–deep-level defect–DLTS

Minority Carrier Trap in n-Type 4H–SiC Schottky Barrier Diodes

Crystals

We present preliminary results on minority carrier traps in as-grown n-type 4H–SiC Schottky barrier diodes. The minority carrier traps are crucial for charge trapping and recombination processes. In this study, minority carrier traps were investigated by means of minority carrier transient spectroscopy (MCTS) and high-resolution Laplace-MCTS measurements. A single minority carrier trap with its energy level position at Ev + 0.28 eV was detected and assigned to boron-related defects.

A Study of Inhomogeneous Schottky Diodes on n-Type 4H-SiC

Materials Science Forum, 2006

We investigated arrays of Ni, Pt, or Ti Schottky diodes on n-type 4H-SiC epitaxial layers using current-voltage ͑I-V͒ measurements, electron beam induced current ͑EBIC͒, polarized light microscopy, x-ray topography, and depth-resolved cathodoluminescence spectroscopy. A significant percentage of diodes ͑ϳ7 % -30% depending on epitaxial growth method and diode size͒ displayed "nonideal" or inhomogeneous barrier height characteristics. We used a thermionic emission model based on two parallel diodes to determine the barrier heights and ideality factors of high-and low-barrier regions within individual nonideal diodes. Whereas high-barrier barrier heights increased with metal work function, low-barrier barrier heights remained constant at ϳ0.60, 0.85, and 1.05 eV. The sources of these nonidealities were investigated with a variety of spectroscopic and imaging techniques to determine the nature and energy levels of the defects. EBIC indicated that clusters of defects occurred in all inhomogeneous diodes. Cathodoluminescence spectra revealed additional peaks in the nonideal diodes at 2.65, 2.40, and 2.20 eV, which complement the low-barrier barrier heights. It is proposed that defect clusters act to locally pin the Fermi level, creating localized low-barrier patches, which account for the inhomogeneous electrical characteristics.