ON THE GATE-VOLTAGE AND DRAIN-VOLTAGE DEPENDENCE OF THE RTS AMPLITUDE IN SUBMICRON MOSTS

The experimental gate- (V(GS)) and drain-voltage (V(DS)) dependence of the fractional Random Telegraph Signal (RTS) amplitude DELTAI(D)/I(D), obtained on a large series of submicron Metal-Oxide Semiconductor Transistors (MOSTs), is reported. The observed variation of the RTS amplitude in linear operation is discussed in view of recently published models. As will be shown, the large spread in weak-inversion amplitudes can only be explained by taking into account the microscopic nature of the oxide trap and its environment. The position of a trap along the channel can in principle be retrieved from studying the so-called RTS amplitude asymmetry, defined as the V(DS) dependence of the amplitude in both normal and reverse operation of the transistor. Widely different asymmetry behaviour is observed in this work. Here, a qualitative model will be derived which gives a more refined analysis and offers some deeper insight than existing theories. However, to fully understand the RTS amplitude in weak inversion, more microscopic detail is needed.