Temperature dependence and irradiation response of 1/f-noise in MOSFETs

Measured the 1/f-noise of 3 μm×16 μm nMOS transistors with gate-oxide thickness of 48 nm as a function of frequency (f), gate voltage (V_g), and temperature (T). For a temperature range of 85 K≤T≤320 K, noise measurements were performed at frequencies of 0.3 Hz≤f≤1 kHz with V_g-V_th=2 V, where V_th is the threshold voltage. Devices were operated in strong inversion in their linear regimes. A detailed comparison of the temperature and frequency dependences of the 1/f-noise of MOS transistors shows the importance of thermally activated charge exchange between the Si channel and defects in the oxide. After X-ray irradiation, the noise power increases after positive-bias irradiation and decreases after postirradiation annealing, in agreement with previous work. For these devices and experimental conditions, detailed comparisons of the temperature dependencies of the noise magnitude and frequency dependence show that the 1/f-noise of nMOS transistors is very well described by the model of Dutta and Horn. As a result, we are able to extract the energy distributions before and after irradiation for the near-interfacial oxide (border) traps that cause the majority of the noise.