Charge Losses of N-Doped Trench Cells

N-doped trench cells exhibit increased charge losses during the refresh time interval when the cell plate voltage is reduced below 2.5 V. This effect is attributed to tunneling of electrons from the valence band of the n-region into the conduction band thus contributing to the leakage current of the cell. This is verified by numerical simulations which indicate that tunneling will occur preferently at the upper corners of the trench. The tunneling current is calculated based on a modified WKB-approximation using 2D potential and imref distributions.