Determination of insulator bulk trapped charge densities and centroids from photocurrent‐voltage charactersitcs of MOS structures

A new rapid technique for determining the density and centroid of trapped space charge in MOS structures is described. Photocurrent‐voltage characteristics for both the metal‐oxide and Si‐oxide interfaces are used to determine the internal fields due to bulk trapped charge and, hence, its density and centroid. An experimental example of this technique is shown for a MOWOS (metal‐SiO2‐W‐SiO2‐Si) structure where a layer of approximately 1014 W atoms/cm2 deposited 80 or 42 A from the Si‐SiO2 interface and charged by internal photoemission is investigated. This technique is compared to others in terms of its direct, rapid, minimally perturbing, low‐current and low‐field characteristics.