Yue Pan

Improvement of Schottky power diode performance by electrode geometry and surround trenching of Schottky contact

This work aims to improve the performance of SiC Schottky power diode with the alternative approach by using trenching around the Schottky electrode. The research was done with PATRAN, a finite modelling method (FEM). The modelling was done with the building of samples with different geometries into two types (the first without trenching around the Schottky electrode and the second was with trenching around Schottky electrode) with the same current through put for every models from both groups). The results show that there is big improvement as the Schottky electrode can take as much as two times the current with the trenching samples in comparison to the non-trenched samples.

Determining specific contact resistivity of contacts to bulk semiconductor using a two-contact circular test structure

We present a numerical method to extract specific contact resistivity (SCR) for three-dimensional (3-D) contact structures using a two-electrode test structure. This method was developed using Finite Element Modeling (FEM). Experimental measurements were performed for contacts of 200 nm nickel (Ni) to p⁺-type germanium (Ge) substrates. The SCR obtained was (2.3-27) ×10^-6 Ω·cm².

Designing geometry for the circular transmission line model to determine sheet resistance under contacts

The Circular Transmission Line Model (CTLM) can be used as a convenient tool for determining the sheet resistance under an ohmic contact. However the model assumes that electrodes are at an equipotential and in order to examine this assumption, an investigation has been undertaken to show the minimum requirements for attaining reliable measurements. Using test structures of nickel deposited on germanium it has been shown that the geometry of the structure has a significant impact on results obtained. In addition to this, care should be taken when testing samples to ensure that suitable probe positions and a sufficient number of probes are used.

Low specific contact resistivity nickel to silicon carbide determined using a two contact circular test structure

We present the experimentally determined specific contact resistivity of as deposited nickel to highly doped n-type 3-C silicon carbide using a novel test structure. The specific contact resistivity, extracted using this test structure and the corresponding methodology, is (0.8-5.7)×10^-6 Ω·cm².

Improved geometrical design of the circular transmission line model ohmic contact test structure

This paper proposes a method to determine the design of the Circular Transmission Line Model (CTLM) in order to ensure accurate results are obtained. The CTLM is used to measure the specific contact resistance of a metalsemiconductor barrier. Through analytical modelling it has been shown that the accuracy of the measurements obtained using a particular CTLM pattern, depends on the geometry chosen. By determining which geometries will yield the most sensitive measurement will ensure an accurate result when compared to the sheet resistance and specific contact resistance of an ohmic contact sample. Analysis of the equations reveals that for any given sample a smaller geometry is preferable. This is determined by comparing the differential of specific contact resistance of the sample with the contact end resistance of the test structure. It has been found that for confident results to be obtained then the annular (centre) ring of the structure should be as narrow as is possible within testing constraints.

A novel single dot test structure for determining specific contact resistivity

The specific contact resistivity of a metal-semiconductor ohmic contact can be determined in various ways and several of these use the transmission line model approach. Concentric circular contacts have circular equipotential and using this and the transmission line model equations for such contacts, a new technique for determining specific contact resistivity is presented. An analytical technique is used to determine the error of this structure and the developed analytical equations are presented. Finite-element modeling results for Al-SiC ohmic contacts are presented to validate the analytical equations. The scaling behavior of this structure is also discussed.

Investigating extremely low resistance ohmic contacts to silicon carbide using a novel test structure

Low resistance contracts to highly doped silicon carbide (SiC) are investigated. Using a novel test structure that is easy to fabricate and easy to use, this paper demonstrates how it is used to reliably determine relatively low specific contact resistivities which vary with heat treatment. The test structure requires no error correction and is not affected by parasitic resistances. Using the test structure, small changes in specific contact resistivity are determined for small temperature changes. Results will be presented and discussed on the application of this novel test structure for nickel to highly doped SiC.