A simple non-destructive method for determining the concentration of vacant deep traps in the vicinity of the film–substrate interface under extrinsic illumination is proposed and tested. The proposed technique relies on capacitance–voltage measurements under illumination. An increase in the width of the conductive channel under extrinsic illumination is expressed in terms of the structural parameters and the illumination-induced shift of the inflection point in the capacitance–voltage curve. The experimental results for GaAs epitaxial films are in satisfactory agreement with those obtained by an independent method based on sidegating measurements.

Non-destructive deep trap diagnostics of epitaxial structures

In n -type GaAs thin film structures, the presence of an n - v junction between a low-resistivity film and a semi-insulating compensated substrate causes errors in standard C-V measurements. The true high-frequency capacitance can be measured only with a significant increase in the measuring frequency along with a significant decrease in the amplitude of the applied measuring voltage. The “true” high frequency/low voltage barrier capacitance of n -type GaAs thin film structures is compared with standard measurements.

A. Tybulewicz

Papers

Capacitance-voltage characteristics of thin-film structures made of n-type GaAs