Papers by Keyword: Capture Cross-Section

Abstract: The knowledge of capture properties of electrically active defects is of primary importance as it helps to understand which deep states are effective in controlling the excess free carriers’ lifetime. Combining DLTS capture experiments with thermal emission measurements enables an overall thermodynamic description of deep states, thus making it possible to characterize recombination centers in semiconductor-based devices. In the present study, junction DLTS capture rate measurements were employed to extract the true capture cross-sections (inversely proportional to the carrier lifetime) and capture energy barriers for the main lifetime limiting defects in 4H-SiC (silicon carbide). A peculiar forward bias dependence of the capture parameters was observed for the shallow boron (B) hole trap. Capture rate measurements on the deep boron (D-center) trap also evidenced the presence of two capture mechanisms, thus allowing discrimination of D₁ and D₂ deep states within the D-center DLTS peak. The results were combined with activation energies and apparent capture cross-sections to obtain the free energy (ΔG) of electronic activation for the analysed deep states.

Abstract: A quantitative analysis method was proposed for near-interface oxide traps (NITs) at the SiC-MOS interface. Based on the tunneling capture model for electrons to the traps, characteristic parameters of NITs were clearly extracted from the pulse width dependence of the constant-capacitance deep-level transient spectroscopy (CC-DLTS) signal amplitude measured under isothermal conditions. To exclude capture processes other than direct tunneling, the pulse voltage was set to the flat-band voltage. The validity of the assumed model, in which the majority of the traps are localized at the interface and not distributed through the whole depth of the oxide, was demonstrated through comparison of the experimental results for two samples with different oxide thickness. The density of NITs at the MOS interface fabricated on 4H-SiC oxidized in a N₂O atmosphere slowly decreases with the energy depth. The capture cross-section at the interface has no energy dependence, and has a value of 10^-19 cm².

Abstract: Schottky barrier diodes and junction barrier Schottky diodes are investigated by thermal admittance spectroscopy, and by Capacitance-Voltage measurements. Samples are protected with surrounding junction termination extension and p+ ring. Temperature dependence of the doping level is first calculated. Then admittance spectra allow detecting defects and extracting their activation energies and capture cross sections. Results seem to indicate the presence of interfacial defects and defects due to the implantation process.