ELECTRICAL-PROPERTIES OF SRF2 ON GAAS (100) INTERFACES

In situ rapid annealing, typically at 590-degrees-C for 10 s, has been shown to be useful for improving the interface properties of strontium fluoride (SrF2) films grown epitaxially by a thermal evaporation technique on a GaAs (100) substrate. The electrical properties of the SrF2/GaAs heterojunction were studied by using capacitance-voltage and current-voltage measurements. Capacitance-voltage measurements on a metal-insulator-semiconductor structure show that the reduction in surface state density and the band bending may be controlled externally, indicating an unpinned Fermi level at the SrF2/GaAs interface. Current-voltage measurements for 114 A thick SrF2 films were used to calculate barrier height, which was found to vary 0.63-0.67 eV for different diode and ideality factors approaching unity.