TRAP FILLING MEASUREMENTS TO DETERMINE THE CROSSOVER POINT OF FERMI-LEVEL AND MIDGAP LEVEL IN GAAS BY CONSTANT CAPACITANCE TECHNIQUE

Trap filling measurements on the midgap level in GaAs are carried out under constant capacitance conditions in the emission process. The tra nsient voltage after application of a filling pulse is measured with v arying capture time. A method to obtain the distance lambda1 from the depletion edge to the crossover point of the midgap level and the quas i-Fermi level is proposed for the case of high trap concentration. Fit ting the calculated lambda1 to the experimental results enables estima tion of the capture cross section of electron in the midgap level.