Distribution of potential barrier height local values at Al-SiO2 and Si-SiO2 inter-faces of the metal-oxide-semiconductor structures

In this work studies of barrier height local values are presented. Distribution of the gate-oxide E BG(x, y) and semiconductor-oxide EBS(x, y) barrier height local values have been determined using the photoelectric measurement methods. Two methods were used to obtain the local values of the barrier heights: modified Powell-Berglund method and modified Fowler method. Both methods were modified in such a way as to allow deter-mination of the EBG(x, y) and EBS(x, y) distribution over the gale area using a focused UV light beam of a small diameter d = 0.3 mm. Measurements have been made on a series of Al-SiO2-Si(n+) MOS structures with semitransparent (tA1 = 35 nm) square aluminum gale (1 x 1 mm2). It bas been found that the EBG(x, y) distribution bas a characteristic dome-like shape, with highest values at the center of the gate, lower at the gate edges and still lower at gate corners. On the contrary, the EBS (x, y) distribution is of a random character. Also, in this paper, both barrier height measurements have been compared with the photoelectric effective contact potential difference [fi]MS(x, y) measurements. These results show geod agreement between distribution of the barrier heights EBC(x, y) and EBs(x, y) measurements and independenty determined shape of the ef-fective contact potential difference [fi]M S ( x, y) distribution.