An analysis is presented of the influence of the quasi-neutral base and the back contact on the measured C-V dependence of the Schottky barrier in undoped semi-insulating (USI) GaAs. It is shown that under specific experimental conditions, which include temperature, test signal frequency and sample geometry, routine C-V analysis can be applied to calculate the effective charge in the Schottky barrier, which is controlled by the concentration of fully ionized ELEo/+, native donor-like states, if the capacitance is measured at a sufficiently low test signal frequency. Results of the low-frequency C-V analysis of the Schottky barrier in bulk us GaAs supplied by four different manufacturers are presented. The existence of a depletion regionin USI GaAs under the metal or injecting contact is demonstrated in a convincing way and the concentration of the effective charge in the barrier is determined.
A new modification of DLTS applicable to semi-insulating (SI) materials based on simultaneous capacitance C(t) and ac conductance G(t) transient analysis, Admittance Transient Spectroscopy (ATS), is introduced. Formulas for C( t), G(t), their differential dC(t), dG(t) and correlated Sc(T), SG(T) forms are presented. The most important features of the ATS based on the simulation are summarized. ATS was applied to the investigation of deep-level states in bulk undoped and lowtemperature MBE SI GaAs. Some of the results are briefly discussed in the context of the previously published ones.
Deep states in undoped semi-insulating GaAs with low carbon content were investigated by PICTS and Photo-DLTS. Hall and Photo-Hall measurements proved that peaks observed in Photo-DLTS spectra are due to the electron emission from deep donor states. Other peaks obtained in PICTS spectra were attributed to the hole emission from acceptor states with the apparent energy levels Epa= 0.18, 0.19, 0.21, 0.5 eV. A minimal value of their total concentration except of 0.5 eV level was estimated at about lx1015 ~m -~. The peak of 0.5 eV level with dominant amplitude in detected spectra correlates with the hole emission from EL2+/++ double donor state. The 0.19 and 0.21 levels are most probably related to the double acceptor GaAs antisite. defect.
We analyze the screening length and the base series admittance effect on the measurement of the barrier capacitance and voltage in semi-insulating (SI) semiconductors. Specific experimental conditions are summarized which enable the utilization of C-V analysis in SI materials. It is shown that under such experimental conditions the formula of Sah and Reddi for low-frequency C-V dependence can be applied for the calculation of the concentration of residual shallow impurities. These considerations are applied for the low-frequency C-V analysis of the Schottky barrier in SI GaAs:Cr formed by Au contact and the concentration of residual shallow donors is determined. Some limitations of the presented C-V analysis are discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.