Keywords: ultra–thin oxide, MOS capacitors, p substrate, n substrate, deep depletion, Schottky barrier, fringing field, gate leakage current, oxide quality
Intrinsic I–V and C–V characteristics of ultra–thin oxide MOS (p) and MOS (n) structures under deep depletion
Ultra–thin oxide MOS (p) and MOS (n) capacitors were used in this study to discuss their intrinsic I–V and C–V characteristics under deep depletion. Through deep depletion analysis proposed by Cheng and Hwu , we found that the gate leakage current of MOS (p) was perimeter–dependent while MOS (n) was area–dependent. These suggest a strong indication of Schottky barrier height lowering for holes in MOS (p) owing to larger voltage drop on oxide at edge region as the result of fringing field effect . Furthermore, MOS (p) and MOS (n) were put under illumination to investigate the non–uniform movement of minority carriers. As expected, minority carriers of MOS (n) have shorter response time because of comprehensive tunnelling current comparing to MOS (p). A thorough understanding of MOS (p) and MOS (n) under deep depletion was presented. In addition, deep depletion as a tool to investigate the oxide quality was demonstrated.