A novel measurement method of the spatial carrier lifetime profile based on the OCVD technique

Using an original test structure we show by numerical simulations that the open circuit voltage decay (OCVD) method can be improved to obtain the spatial profile of the τ_PO, τ_NO lifetime parameters along the epilayer of n-n+ wafers. The test structure consists of a surface diode including an additional n⁺ region, where the diode is used to inject minority carriers within the epilayer, the sense region allows one to measure the diode voltage without the series resistance effect, and finally a positive voltage applied to the n+ substrate is used to electrically control the epilayer volume where carriers recombine.