Papers by Keyword: p-Type SiC

Abstract: Heavily p-type doped (P⁺) implants are commonly used to achieve low specific contact resistance (SCR) for p-body diodes through a costly ion implantation process. Alternatively, our study proposes a single-step plasma treatment method using BCl₃ plasma. This method incorporated a high concentration of self-activated p-type boron dopants in the SiC lattice with minimal damage. Experimental I-V data from Schottky Barrier Diodes (SBDs), combined with TCAD simulation, demonstrated that approximately 40 % of boron atoms were activated in the SiC lattice (at a depth of 30-40 nm) without the need for high temperature ion implant activation. Our approach using plasma treatment realizes an SCR value ρ_c of ~ 5.6×10^-5 Ω∙cm², which is approximately 1 order of magnitude lower than that of untreated samples.

Abstract: In this paper we study and compare two designs of a temperature sensor monolithically integrated to a vertical SiC JFET. One sensor utilizes the standard JFET P+ aluminum gate implantation scheme. The advantage of this sensor is that the integration with a JFET process flow can be achieved with no additional process steps or mask layers. The other sensor uses a combination P-body and a low energy P+ implantation scheme, typically seen in MOSFETs. Both sensors exploit the variation of resistance with temperature of Al doped SiC. Drift-Diffusion simulations of both designs are carried out at fixed temperatures, exhibiting an excellent ~53% relative reduction in sensor resistance from 300 to 450K. However, neither design shows linear behavior with temperature, beginning to saturate at 450K. Electrothermal simulations are also deployed to verify the sensor robustness as the sensor is locate relatively far from the JFET junction. Due to the high thermal conductivity of SiC, the sensor average temperature follows closely the junction temperature. Current crowding (or 2D effects) close to the contact edges is observed in both sensors. We also deploy a simple analytical model to calculate the resistance as a function of the temperature for both sensors. The model agrees with the drift-diffusion calculations, however due to the 2D nature of current flow, a maximum 19.6% relative error is obtained. In general, both sensors deployed similar relative sensitivity, however the P-body sensor resistance changes in a range of 10.6kΩ to 4.95kΩ compared to 700Ω to 330Ω for the P+ sensor.

Abstract: Carrier removal rate (Vd) in p-6H-SiC in its irradiation with 8 MeV protons has been studied. p-6H-SiC samples were produced by sublimation in a vacuum. Vd was determined by analysis of capacitance-voltage characteristics and from results of Hall effect measurements. It was found that full compensation of samples with initial value of Na-Nd 1.5 x1018 cm-3 occurs at an irradiation dose of ~1.1 1016 cm-2. In this case, the carrier removal rate was ~130 cm-1

Abstract: 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.

Abstract: The long term performance of today’s SiC based bipolar power devices suffer strongly from stacking fault formation caused by slip of basal plane dislocations, the latter often originating from the n-type doped SiC substrate wafer. In this paper, using sequentially p-type / n-type / p-type doped SiC crystals, we address the question, whether basal plane dislocation generation and annihilation behaves differently in n-type and p-type SiC. We have found that basal plane dislocations are absent or at least appear significantly less pronounced in p-type doped SiC, which may become of great importance for the stacking fault problem in SiC.