DETERMINATION OF THE ALUMINUM-INDUCED OXIDE CHARGE BY AC SURFACE PHOTO VOLTAGE MEASUREMENTS IN N-TYPE SILICON

摘要

An alternating-current surface photovoltage (ac SPV) technique has been employed to investigate how the ac SPV in aluminum (Al)-contaminated n-type silicon (Si) wafers varies with exposure time to air and as a function of frequency. The (AlOSi)~- network which is responsible for negative oxide charge increased with exposure time to air, resulting in a progression from a depleted and /or weak inversion state to a strong inversion state. Based on Munakata's half-sided junction model, calculation of the oxide charge density showed that about 4 % of the Al concentration in the native oxide was activated as the (AlOSi)~- network when the native oxide of the Al-contaminated wafer was exposed for 1 hour in air. Fe also acted as a negative charge in the form of an (FeOSi)~- network in the native oxide. This Al- and Fe-induced negative charge is named the metal-induced negative charge (Q_(mi)).