Understanding threshold voltage in undoped-body MOSFETs: An appraisal of various criteria

Undoped-body MOSFETs are currently becoming increasingly important and the value of threshold voltage is often used to assess the reliability of fabricated devices. However there exists a disparity of threshold voltage criteria proposed for these novel devices. The concept of threshold voltage in undoped-body MOSFETs is examined and various existing criteria are analyzed and compared in an effort to clarify the ambiguity of the meaning of threshold and understand its dependence on technological parameters in these devices. Phenomenological considerations are also presented to shed light on the behavior of the sub-threshold slope with changing semiconductor body thickness.